The Witcher 3 Enhanced Edition Mod

Stats:

Vitality:
Vitality governs your overall well-being. Instead of simply being a number that signals how far you are from death, it has effects on many other things in the mod. The lower your vitality is, the lower your regeneration rates are for other stats as well.
If you are on the verge of death, your Stamina and Vigor will regenerate exceedingly slowly, your Attack Speed will slow down and Poise will be a mere dream of the past. In other words, getting hit is bad; it'll fucking hurt and you'll actually feel like you're dying. Makes sense.

Stamina:
Stamina governs your overall strength and endurance. It is no longer used to cast signs, but to perform attacks, dodge, parry and counter incoming blows, sprint, jump, etc.
As your Stamina lowers and you become tired, your general movement and attacks will become slower and your Attack Power will lower (up to 40% reduction at no Stamina).
Stamina regeneration depends on many factors: Having low Vitality and high Toxicity will slow down your Stamina regeneration, while having high Adrenaline will speed up the regeneration substantially. Having no Stamina at all will also make you unable to attack, dodge and counter incoming blows.
Don't overexert yourself too quickly in combat by making poor decisions or you'll end up as a corpse rather quickly.

Adrenaline:
Adrenaline is exactly what it sounds like. It only builds up during combat by performing successful attacks and counters and greatly improves the flow if you play well. All adrenaline is lost upon getting hit, but while available it will speed up Stamina and Vigor regeneration,
letting you keep up your rhythm in combat without having to wait for your stats to regenerate at their normal rates. Keeping your Adrenaline high can be a quick way to victory.

Toxicity:
Toxicity is the amount of poisoning your body can endure. All potions and decoctions build up Toxicity when consumed, which, if too high, will start to drain Vitality at an exponentially faster rate the closer it is to the maximum. The normal Toxicity threshold is 50, after which point Vitality will get drained depending on how much Toxicity you currently have compared to your maximum amount.
Meditation raises the Toxicity threshold by an additional 20% of your maximum Toxicity value, allowing you to effectively control your bloodstream and wait until the negative effects of potion consumption wear off if you didn't poison yourself too much.
Having high Toxicity impedes Stamina and Vigor regeneration, but by making you more numb to pain, it also raises your Poise value.

The Toxicity of potions will remain latent for most of their duration, very slowly waning away. When the potions' effects are starting to wear off, so will their Toxicity until it is completely cleared from your system. Decoctions have a set Toxicity value and they will not decrease slowly while in use, instead completely wearing off as soon as the effect of the decoction passes.
Drinking multiple decoctions also increases the severity of other Toxicity effects, which means that drinking several decoctions or decoctions combined with several potions is hardly possible unless the maximum tolerance is really high.
Toxicity is something to be very mindful of, seeing how it can easily end up killing you. Drink responsibly (McButtfuck Life Advice™) and prepare properly before fights while paying attention to the potential secondary ingredients potions can take on by using the correct ingredients.

Vigor:
Vigor is essentially your pool of magical power and is used to cast witcher's signs while also giving you passive bonuses. If Vigor is depleted, you will be unable to cast any signs. While staying latent and unused, it raises your melee damage and possibly other stats with the correct talents.
You have 3 points of Vigor by default, each sign cast costing a single point. The lower your Vigor is compared to the maximum value, the lower the intensity of the signs you can cast. Getting hit also hurts concentration and drains Vigor depending on the type of the incoming attack and its severity. The less damage you take, the less Vigor you will lose.
Casting a sign imposes a 2.5 second regeneration delay by default during which Vigor will not regenerate; the same is true for while the Quen sign is in active use.

Poise :
Poise is your ability to withstand the force of incoming attacks without being staggered or getting your attacks interrupted. Each point of Poise constitutes a 1% chance to resist the force of an incoming blow. While offering a form of resistance, Poise does not negate all forms of incoming stagger, negating only those from regular hits that you would be able to parry by conventional means.
Having a Poise value of over or equal to 110 allows you to withstand the force of blows that you would be unable to parry as well. The amount of Poise you have is governed by several things, such as Vitality, Toxicity, active mutagens, armor worn, your momentum and even some potions.
The heavier the armor worn, the more Poise it will grant. Active red mutagens also increase Poise according to their potency as well as your maximum Vitality, while also benefitting from the Synergy alchemy talent. Attacking, running, sprinting, jumping and dodging also give you momentum, increasing the amount of poise you have by a certain percentage.

Attack and Evasion Speed:
The speed stats govern the speed of your blows and evasive action such as dodging and rolling. Being hurt, tired and wearing heavy armor all lower attack speed, but it can also be raised by taking the correct talents and drinking certain potions.

Gameplay Mechanics:

Regular Attacks:
Performing regular light and heavy attacks now also costs Stamina like most other actions. You can not perform any type of attack while you are out of Stamina, but attacking an opponent also stops their Stamina regeneration for half a second.
The default combat animations have been changed to ones without stationary spins to make combat feel more... "grounded" in a sense. Both swords and secondary weapons have new and distinct movesets to set them apart from one another as well.
Regular attacks are divided up into 3 attack ranges: close range, medium range and long range. The longer range attacks cost more and are slower than the ones that are shorter range.
In addition, mashing the attack button will make your regular attacks fail, costing you more stamina, losing a lot of speed and staggering you on parried hits.

Targeting:
There are four targeting types in the mod, namely: manual targeting aimed with the camera, manual targeting aimed with movement directions, soft lock with a more solid and customizable behaviour than vanilla, and lastly, the vanilla soft lock targeting.
Manual targeting disables the behaviour that has Geralt focus on a single enemy and lets you attack wherever you damn well please, even if you miss like a complete fumbling retard. You have full control over all your offensive and defensive actions this way.
The automatic targeting option keeps to the vanilla design, but uses the improved soft lock behaviour by default, where you can modify the different weights based on which the game chooses your opponents and how it should prioritize changing active targets.

The manual targeting for bombs has also been changed and instead of an inaccurate crosshair, you will now have a marker on the ground where the bomb would land if you were to throw it. This improves accuracy by miles and reduces headaches as well.

Weapon Type Mechanics:
The weapon type mechanics have been changed in a way so that you rarely need to use your silver sword anymore.
Steel and silver swords have both a 'Steel Damage' and 'Silver Damage' stat:
- Steel Damage meaning how much damage is dealt to humans and non-humans.
- Silver how much damage is dealt to monsters.
This means every monster can be killed with steel swords, while silver swords can be used to kill human and non-human opponents. The exception to this are Specters, Cursed Ones and Vampires, who can still only be slain by silver swords.

Parrying:
The second most important defensive tool in your arsenal, parrying should often be used against both human and smaller monster opponents to easily avoid damage at a minimal Stamina cost. The Stamina cost for parrying attacks is not uniform, meaning that parrying a heavy attack or an unblockable attack will cost more Stamina than parrying a light attack.
If no Stamina is available whatsoever, you can still perform partial parries. Partial parries don't completely block all incoming damage, but they still stop most negative effects and injuries from happening.
Performing a partial parry against an incoming light attack will still let 10% of the damage through and cancel any negative effects it might have had while keeping you in your parry stance. Performing a partial parry against an incoming heavy attack will let 20% of the damage through and cancel bleeding/poison effects, but will still leave you susceptible to knockdown and will break your block.
There are attack types which can not be parried, such as two handed axes, hammers, strikes from large monsters, etc. Performing a parry against one of these attacks will still cancel negative effects like bleeding or poisoning, but it will let 30% of the incoming damage through while also staggering you for a long time, leaving you open to subsequent attacks. It's still preferable to taking a full-on hit in a one versus one situation.

Countering:
Countering is the most important defensive tool you have and the one that will probably see the most use. Countering, same as parrying, has different Stamina costs for different types of attacks, difference being that countering can not be used at all while out of Stamina.
Almost any type of attack can be countered, except area of effect attacks and most projectiles; you can even counter an opponent's counterattack right back. Countering an attack usually negates all of its damage and any negative status effects it may carry with it, while also subsequently leaving the opponent open for one of the three counter reactions you can perform. Countering incoming heavy attacks, for example those of large monsters, warhammers, battleaxes and so on will only perform a partial counter, but still retain all of the effects of regular counters except the full damage reduction.
The three counter reactions are: sword slash, kick and a strong bash. These all have different effects, some depending on enemy types, which can also be enhanced with acquired talents in the Defense skill tree.

Counter reactions can be chosen according to taste via the mod menu or the provided hotkeys, or, if all options are set to the sword slash type of counter, keyboard and mouse users can easily choose counter types in the heat of combat by holding the medium range attack modifier for a kick or the long range attack modifier for a bash type counter retaliation. If no buttons are pressed other than the counter button, the sword slash will be performed.

Dodging:
Dodging is the third and last type of defensive action you can use. It was majorly changed, in the way that it does not make you invulnerable anymore. Dodging and rolling both cost Stamina (rolling costs a lot more) and can not be performed if no Stamina is available.
Getting hit while dodging away from an opponent (keyword being "away"), you will only receive a small amount of graze damage which can further be lowered by acquiring specific talents. You must be dodging away in a 90 degree angle from an opponent to only receive graze damage, which can also be raised by acquiring specific talents. Dodging towards an opponent will result in full damage being taken.

The role of dodging and rolling has been shifted from being the main source of damage negation to being more of a tactical positioning tool. Damage can still be completely avoided with proper spacing, but it is much more useful for quick positioning in combat or for fleeing a fight you are about to lose.

Jumping:
You can jump in combat. You need to be sprinting to do it.
That's it, I have fuck-all else to say about that.

Special Attacks:
There are two types of new special attacks: a kick, which counts as a light attack, and an injuring heavy attack. Both of these attacks also cost Stamina (more than their normal counterparts) and can not be performed while no Stamina is available.
The kick attack is performed by holding the parry key and pressing light attack. This attack does not work on large opponents. Successfully performing it will result in your opponent being staggered and some Stamina damage being dealt to them, leaving them open for an attack, while successfully performing it on a staggered opponent will have a chance to knock them down.
The injuring heavy attack consists of two heavy slashes which, if they both hit, are guaranteed to apply an injury to most opponents. The second attack also ignores enemy guards. If the attack deals enough damage to bring the opponent below 30% health, a finisher is automatically triggered.
Whirl and Rend can also be used from the start without taking the talents themselves.

Crossbow:
The crossbow has been completely changed and is now a somewhat useful tool in your arsenal that can deal very real damage to your opponents.
You will no longer have infinite bolts and will need to find/craft/buy bolts to use. They each have their specific tactical use like causing heavy bleeding, piercing through heavy armor or tough hide, staggering opponents or simply dealing tons of damage.
Reloading has also been made slower to reflect the higher power of the crossbow along with changes to the ranged talents to give it more straight combat or tactical uses.

Combat Injuries:
Injuries are another completely new addition to the already deadly combat system the mod features. During engagements, each hit has a chance to also apply an injury based on which body part was hit. There are injury types for arms, legs, the torso and the head, both frontal and dorsal, each carrying with itself a set of painful status effects or maluses that can quickly change the course of combat.
Arm and leg injuries have a chance to make one stagger when attacking, head injuries cause severe damage and incapacitate one for some time, chest and spine injuries cause trauma and heavy bleeding. They can also carry with themselves increased stamina costs or an even bigger damage bonus for the attacker when striking from behind.
Injuries are automatically healed as soon as health is fully replenished and they are also harder to stack the more injuries the victim already has.

Meditation:
A new, core part of the game. Meditating is a witcher's best friend, allowing you to rest, brew potions, learn new talents, improve your gear with runes and glyphs or spend time to meticulously apply oils to your blades or to consume potions in a controlled manner.
If you have firewood and simply enter meditation, Geralt will set a fire, allowing you to brew potions and gain a well-rested bonus if you rest near it for at least six hours. If you hold the meditation key, Geralt will enter meditation without setting a fire.
While meditating, any applied oils gain bonus charges and any potions consumed have a longer duration. Meditating also raises your Toxicity threshold by 20% of your maximum Toxicity.
Holding the meditation key while meditating will bring up the clock menu, allowing you to set a time on the clock until which you want to wait. Alternatively, you can simply hold the sprint button to use real-time meditation and simply speed up the passing of time actively.
When assuming meditation with an active fireplace, Geralt will also whistle for Roach to come and stop nearby, making your stash automatically accessible. Learning new talents and improving your gear is also only possible while meditating and will pass time.

Alchemy:
Alchemy has been completely overhauled and is now a much more invested process for a possibly large payoff.
Instead of requiring specific ingredients, alchemical items now require certain substances: Vitriol, Rebis, Aether, Quebrith, Hydragenum and Vermilion. Plants and monster parts all contain these core substances in some form or another and they can be interchanged during the alchemical process by clicking on the ingredient icons and using the hotkeys shown in the menu.
While all ingredients contain these substances, not all ingredients are created equal. Some ingredients will only be a low source of a substance, while other (usually much rarer) ingredients can be rich sources.
The type of source an ingredient is determines how much of it you will need to brew a certain potion, so as to achieve the proper potency.

Potions, oils and bombs are all created on an individual basis and you can create and stack as many of them as you would like. If you want to carry with you a cart of Swallow potions, you will be able to do so now.

Ingredients can also be sources of secondary substances: Albedo, Rubedo and Nigredo. These secondary substances, when matched up, yield a potion with an additional beneficial effect in addition to its usual effects.
Albedo potions lower the Toxicity of subsequently consumed potions, allowing you to drink more of them; Rubedo potions grant Vitality regeneration, while Nigredo potions increase your overall damage dealt.

When creating an alchemical, the ingredients will be used up and the item will be added into a queue. When exiting the alchemy menu, the brewing process will start and some time will pass based on the types of items you are creating and the number of ingredients used. After the time is up, all your items will be added to your inventory.

Gathering herbs has also been made a lot easier by greatly increasing the amount a single plant gives. It is also possible to harvest ingredients while on horseback for added ease and comfort.

Cooking:
Added cooking and cooking recipes to be bought from innkeepers. That kinda sums that up.

Animated Actions:
Drinking, eating, oiling your sword and picking herbs all have their very own animations set up. No longer will you instantly enjoy the benefits of a potion in the middle of a fight without creating a small opening to actually drink it.

Finishers:
Finishers have been turned into an actual active game mechanic instead of simply eye-candy.
They can only be triggered manually now, but upon executing someone, you instantly gain back a chunk of Stamina as part of an adrenaline burst; the drawback is that you are completely vulnerable while performing them.
On the flip side, you can control what type of finisher you want to play by using the movement keys while triggering them. Holding forward will perform an animation that is also an attack forward, holding left will perform an animation that is also an attack left. You can try and fend off enemies this way while performing finishers in the middle of combat.

Night Sight:
Geralt can now dilate his pupils at will like he's supposed to be able to. The Cat potion has been replaced with a dedicated hotkey to toggle night sight instead of having to fumble around with an annoying potion.

Improved NPC Behaviour:
NPCs aren't completely inept anymore and are much more relentless in their attacks both against you and each other. Their parrying and countering behaviour has also been much improved, making them parry strikes in a more sensical manner while also countering you if you engage in Pavlovian button mashing tactics.
They also no longer suffer from "Action Movie Bad Guy Syndrome" as much, where they would politely wait for you to finish your attacks and attack you one by one in a very orderly fashion to not make your job too hard. You actually have to watch out for skilled fighters now.
Don't worry, though. Hobos are still hobos.

New Weapon Types:
Battleaxes and battlemaces have been added as new weapon types, coming with their own movesets, benefits and drawbacks. They hit hard, are very hard to counter, have a higher chance to injure opponents, but are also heavier, slower, require more Stamina and they only have close range attacks, requiring very good spacing abilities from its wielder.
Diagrams for specialized witcher versions of these weapons can be bought from the master blacksmith in the city of Novigrad.

Runewords and Glyphwords:
Runewords have been completely remade and now there are only 3 types you can use, but all 3 of them also have 3 levels. They are also tiered now, which means that you need the previous level enchantment to apply a higher level one.
Glyphwords have been rebalanced; some have also been removed or their use completely changed to fit in better with the new mechanics.

Unleveled World:

General Information:
The main focus of the mod, the unleveled word of Witcher 3 allows you to go anywhere you please at any time in the game as long as you have the necessary resources and/or skill to do so. There is nothing holding you back from heading off to do the expansions right after you finished the prologue area... although this also brings some "drawbacks" with itself.
While difficulty is not really the aim of the mod, it is MUCH harder than the vanilla game ever could be. The baseline of the mod is Normal difficulty, the others are basically as their in-game description states. This is what it was designed around and what it works best with. That is not to say other difficulty levels do not work, just that Normal is the intended one.

Unleveled NPCs:
NPCs do not have levels anymore, thus offering a more logical and internally consistent gameworld. All enemies have uniquely defined stats corresponding to their lore, looks and monster type. You will no longer faace nekkers that are stronger than ekimmaras or run into a pack of wild dogs that die in one hit right after you ran away from a different pack of wild dogs that had godlike stats. Nekkers are nekkers, dogs are dogs, ekimmaras are ekimmaras. No confusion, no headaches.
That being said, the NPC disparity mechanic makes sure not every NPC is an exact carbon copy, but instead each and every NPC has unique, variable stats fluctuating around the base stats of their types. Some humans will have more Stamina than others or be better at parrying than others, while some might have lower Vitality but be better at countering incoming blows. No two enemies are exactly the same anymore!
Every NPC is balanced in a way to make them challenging, but also beatable at any point throughout the game, offering you as much freedom as you desire, or as much as you can muster based on how skilled you are at playing and how much you prepared for fights.

The Bestiary:
The bestiary has been expanded drastically and now includes all monster entries by default. Every single entry was expanded with tactical information, correct weaknesses and a description of the monster's behaviour to aid in preparation.
There are often tactics that are described in the new entries as well, which can help in deciding on an initial approach to a fight.

Progression:
Player progression is handled organically in the mod, through exploration, combat, alchemy, questing and finding/crafting new gear. Geralt will still get stronger as you keep unlocking new talents just like before, except that the system you achieve progress through has been completely changed.
Skill points are acquired organically through gameplay by performing regular tasks that befit your playstyle. Using heavy or light attacks raises your heavy or light attack progression; dodging, rolling, parrying and countering raises your defense progression; shooting your crossbow raises your ranged progression; generally being in combat raises your battle trance progression;
casting signs raises your appropriate sign progression; creating potions, oils and bombs raises your appropriate progression level; distilling ingredients and creating decoctions raises your mutation progression; exposing yourself to Toxicity raises your trial of the grasses progression and finding new locations and completing quests progresses your general skills.

When a skill path's progression reaches a hundred percent, you are granted a skill point that you can only use in that assigned skill path. The more skill points you earned for a path overall, the slower the skill progression for that path will be. You can no longer learn talents for skills that you have never used anymore.

Talents and Mutagens:
Talents are learned by spending skill points for the specific skill paths they are available to. You can pick any talent from a specific skill path without restriction and learn it while meditating and passing time. It is also possible to preview later levels of talents by using the hotkeys displayed at the bottom of the menu.
They are active by default and don't have to be equipped into slots to work. The slots are there for mutagen synergies and are unlocked by earning more overall skill points. Synergising talents with mutagens increases the power of the equipped mutagens; the more talents equipped, the stronger the mutagens are.
Green mutagens increase maximum Toxicity, blue mutagens increase Vigor regeneration speed, while red mutagens increase maximum Vitality and Poise.

Loot Scarcity:
The amount of loot that can be found in the world has been greatly reduced. Most containers will not have any loot at all, while the ones that do will not contain relics of fabled power, scattered around randomly without reason.
Relic items can only be acquired via crafting after finding their associated diagrams, and more expensive or rare items can also only be acquired from more important locations.

Economy:
The economy has been completely changed. The changes are supposed to reflect that witchers live in relative poverty, as stated in the books.
Loot is not your main source of income anymore. Monster contracts are the best way to earn crowns so haggling has been made a much more important mechanic, allowing you to get fairly high bonuses on rewards if you press hard enough.
The prices of all items have been drastically reduced and there is a lot less money in circulation in the world than before. You won't be able to amass insane amounts of wealth anymore and with the scarcity of loot, you will be actually required to buy items from merchants, running out of money quite often in the process.

Crafting and repairing prices have also been rebalanced and will actually take a toll on your finances.

Inventory:
Inventory management has been changed a lot. You can't carry too much anymore since you're not a packmule, instead, the load is transferred onto Roach, who is now also a portable stash in addition to being a means of transport.
Stash mechanics have been changed a lot, allowing you to automatically transfer miscellaneous items to your stash and to sort items in it by category for easier management. Saddlebags no longer increase your own carryweight, but instead Roach's carryweight. When performing alchemy or crafting items, everything stored in the stash is automatically accessible for ease of use; same is true for money.

While browsing merchant inventories or the dismantling / repair categories at smiths, you can also press the corresponding hotkey displayed at the bottom of the menu to toggle between your own inventory and Roach's inventory, letting you dismantle or repair equipment or to purchase things straight into Roach's inventory.

Gear and Resistances:

Player Gear:
The quality of your gear depends completely on... well, its quality. Common gear will be nowhere near as good as magical, relic or witcher gear in any respect, be it protection, damage or durability.
Armor weights were all properly rebalanced and they are divided up into 3 types: light, medium and heavy armors. Every armor you can wear has 2 types of protection: Damage Threshold and Damage Resistance. Damage Threshold constitutes the regular armor value they show, while the resistances are on a per-damage-type basis and are listed under the equipment stats.
Each and every armor type has its own distinct qualities and playstyles, with light armor offering lower protection than any medium or heavy armor, but keeping you fast and your Stamina usage low. In contrast, heavy armor has the highest resistances out of all armor types, but it slows you down and penalizes you Stamina-wise. Medium armor is a "best of both worlds" type of armor, keeping a balance between protection, speed and stamina usage. Going in completely naked is also a valid choice, making you more agile than if you wore any armor.

Weapons follow the same formula as armors, except their damage does not vary too much even between quality types. A sword is a sword and unless it's dull, very rusty or really badly made, it will kill things perfectly well, but what does differ is the durability of certain types of swords.
Steel swords, being your general use weapon, are fairly durable, especially when they are high quality, but the same can not be said of silver swords. While their steel core does offer them a solid base, silver is easily dulled and thus won't last long if you keep using it constantly without proper care.
Secondary weapons like smaller axes, hatchets and maces also deal less damage than swords do, but they usually come with hefty armor piercing values, something that is essential in taking down heavily armored foes or opponents with really tough hides.

Special Gear:
There are several new special items added by the mod which all come with their unique properties and benefits. Items like the Winter's Blade, which is now actually true to its name; Aerondight, which has infinite durability and counts as both a steel and silver blade by default; Iris, which can unleash fiery hell on opponents, the newly added relic weapons or the specially designed plate armor sets that can be acquired from the grandmaster smith in Touissant all offer something new and powerful to look for during your adventures.
The new witcher-specific weapon types the master blacksmith in Novigrad can craft for you belong in this category as well, offering a small, but interesting twist to gameplay.

NPC Stats and Resistances:
Since NPCs are all unleveled along with the player, they all have unique stats and resistances befitting their species, or, in the case of human opponents, befitting their armor and their weapons. NPCs without armor wielding a club will be very weak both health, resistance and damage-wise, while ones clad in plate with longswords will have much less trouble giving you a really bad time.
Monsters also have status effect resistances based on their species (drowners and ghouls are resistant to poison, for example), while humans have resistances based on their equipment. In the case of monsters, it's an innate resistance, so both the chance to apply these effects and their damage when applied is reduced.
In the case of humans, since they rely on armor for protection, only the chance to apply the effects is reduced and not their damage, making DoT effects very effective against human opponents, seeing how they largely have the same health pool no matter what armor they're wearing.

NPC Resistances are fairly easy to gauge just by their looks (or very easy in the case of humans), but in the case of monsters, the bestiary usually offers tips on what they are weak and what they are resistant against.

Armor Piercing:
Armor piercing is one of the two most important stats weapons (and monsters' strikes) have, right along their actual damage. NPCs, as well as you, can have quite a lot of armor which high damage doesn't really help against too much on its own.
That point is where armor piercing comes in, letting you effectively negate a part of the opponent's protection and have more of the weapon's damage go through in the process. Armor piercing varies from NPC to NPC, with some having problems even against medium armor, while others almost completely ignore the armor their opponents have, like golems.
This is what sets apart specific weapon types, such as maces and swords. While swords deal higher damage than maces do, if your opponent is turtled up in plate armor, the mace will do more damage than the sword. Armor piercing can also be gained through the use of specific runes, which can greatly increase a sword's effectiveness against certain NPCs.

Signs:

Aard:
Aard is a very general use sign, potentially specializing in both damage-dealing and crowd control. The standard cast version of Aard is normally okay at crowd control and can be upgraded into a very strong damage-dealing tool, force damage being stronger than the fire damage Igni can deal, which is more situational.
The alternate cast version of Aard deals low damage even when fully upgraded, but has a way higher chance of knockdown and is also an area of effect attack, making it the strongest general crowd control tool you can have.
You can also cast Aard underwater, generating immense pressure and generally squishing everything the shockwave makes contact with.

Igni:
Igni is a highly situational sign, but a very useful one when the time is right. The standard cast deals a nice amount of damage, but its main use is crowd control, which it excels at against certain enemies, especially when upgraded. Opponents set on fire tend to be out of the fight for a long enough time to let you take care of other enemies without fear of much retaliation.
The alternate cast version of Igni excels at dealing an absolutely huge amount of damage against enemies that are weak to fire, making it a very powerful tool against certain enemy types.

Quen:
Quen is a defensive sign, which can be partially upgraded to deal damage (even quite a high amount with a lot of complementary gear and runes). Quen works as an additional layer of armor which decreases incoming damage by the remaining shield health. The remaining damage (if there is any) goes through normally.
The alternate cast version of Quen is also a defensive sign, but it is unique in the sense that the damage that breaks it does not hurt Geralt, but instead imposes a regeneration malus on your Vigor stat, making it effective against huge hits, like a griffin or a golem jumping on you. It is also unique in that reflected damage is much higher than that of the normal shield.
When upgraded with the explosive shield talent, the alternate Quen sign can also be used as a sort of low-cost poor man's Aard, letting you quickly stun enemies around you in a short radius.
Vigor does not regenerate while Quen is active, but the shield can be deactivated at any time by simply pressing the sign cast button again.
You can also cast Quen underwater to achieve a wonderful show of sparks and happiness.

Yrden:
Yrden is a very balanced sign, in the sense that it serves just as much as an offensive sign as it does like a defensive one. By default, enemies that enter and Yrden glyph are slowed down, allowing you to mount an offensive against them more easily, but it can also be upgraded to deal constant damage to opponents inside the circle, making it a great damaging instrument and also very good at stopping the health regeneration effect of certain foes.
The alternate cast version of Yrden is more offense-oriented than its normal counterpart, but it can also be upgraded to have partial crowd control effects by slowing down enemies it hits for a short amount of time.
Yrden is also very useful against specters, both negating their essence regeneration and keeping them in their material form.

Axii:
Axii is a strictly non-offensive sign, focusing on single target (and later up to 4 target) crowd control. A successful cast of Axii puts a target out of the fight for quite a while by stunning them in place, allowing you to either focus on different enemies or get a free hit in from the back on the one you stunned. When upgraded, Axii can become quite a strong crowd control tool, allowing you to put multiple opponents out of the fight for a long time.
The alternate cast version of Axii is effectively a mind control spell, allowing you to take control of one or multiple enemies, turning them against their own thus having both a damage dealing and a damage soaking ally on your side.
Axii can also be used to unlock special dialogue during conversations.