Critical Hits, aka Critical Strikes or crits for short, are a game mechanic in Diablo III and subsequent games. Each hit against an enemy has a chance to deal significant extra damage, a critical hit. It is one of the major ways the damage of an attack skill can be increased beyond its base level defined by equipped weapons and the skill itself.
A critical hit has a specific chance of happening, for each enemy hit by an attack. When it occurs, the attack causes additional damage. Monsters usually cannot deliver critical hits, only player characters can. Both the Critical Hit Chance (CHC) and Critical Hit Damage (CHD) bonus are significant character stats, and can be increased by items, skills, and other sources.
Some classes and skills also have special effects that only trigger on a critical strike, such as Arcane Power regained for Wizards. On the other hand, many Damage Over Time attacks cannot be Critical Hits. Instead, they receive a flat bonus to damage based on the expected damage weighted between crits and non-crits, which can be calculated by multiplying Critical Hit Damage by Critical Hit Chance. This way, Damage Over Time still benefits from crit stats, although they will never trigger effects that require a critical hit to happen.
Critical hit mechanics replace (and partially incorporate) many passive weapon effects from Diablo II: slain monsters rest in peace, Deadly Strike, Crushing Blow etc.
An attack that delivered a critical hit uses a different, larger font for its popup damage number.
Diablo III
Critical Hit Chance defaults to 5%. Increased chance is normally rollable on gloves (up to +10%), rings (6%), bracers (6%), amulets (10%), helms (6%) and off-hand items (10%), for a total of +54% maximum from items. Some Legendary or Set items may make different amounts or slots possible, and their unique powers may also modify Critical Hit Chance, for one, some, or all attacks depending on the power.
Critical Hit Damage (CHD) starts at +50%. Bonuses from items are normally possible on gloves (up to +50%), amulets (+100%), and rings (50%), or +250% total. Some Legendary Items can roll this stat on other slots. Emeralds in weapon sockets also increase CHD, by up to +130%, and are generally the most used gem type for weapons because of the significant increase this brings to overall damage.
In Diablo III, when a critical hit kills the enemy, its corpse is destroyed. The animation used depends on the type of damage dealt. For example, Holy damage may cause the target to be vaporized, while Physical damage can tear the victim limb from limb, and Cold damage can freeze the enemy solid, then shatter it, etc. Whatever the case may be, its corpse cannot be revived by other monsters (like Fallen Shamans). Corpses that normally cause on-death damage (Accursed noxious vapors, Molten explosion etc.) are not subject to this effect, so the monster's post-mortem revenge will occur as usual despite the critical hit. These effects only destroy corpses that monsters can use: secondary resource of Necromancers, the corpses only visible to them, remain intact. This includes the Necromancers' own attacks, so they don't leave themselves without fresh bodies with their own critical blows.
Each class has a cap of Critical Hit Chance from items and skills (in addition to 5% innate chance):
- Barbarian: 60% Critical Hit Chance (Battle Rage with Into The Fray stacks infinitely, Overpower with Killing Spree adds 8% for 5 seconds, Revenge with Best Served Cold adds 8% for 6 seconds, Wrath of the Berserker adds 10%, Weapons Master adds 5% for Mace and Axe weapons)
- Demon Hunter: 56% Critical Hit Chance (Sharpshooter passive skill can make it up to 100%, and additional 10% for Caltrops with Bait the Trap; Vault with Action Shot are guaranteed Critical Hits; with Archery, Hand Crossbows gain additional +5%; Single Out adds +25%; Wind Chill adds +8%)
- Monk: 58% Critical Hit Chance
- Necromancer: 58% Critical Hit Chance
- Crusader: 58% Critical Hit Chance (Judgment with Resolved effectively adds +8%; Bombardment with Annihilate rune will always deliver critical hits)
- Wizard: 58% Critical Hit Chance (Conflagration effectively adds another 6%, Energy Armor with Pinpoint Barrier adds 5%, and 10% temporary bonus from Frost Nova with Deep Freeze)
- Witch Doctor: 58%
In addition to those bonuses, Paragon levels can add up to +5% more critical hit chance and +50% critical hit damage. Shi Mizu's Haori and Broken Promises make all hits guaranteed Critical Hits on certain conditions.
Obviously, Critical Hit Chance is capped at 100% (achievable by legitimate means). Critical Hit Damage has no cap other than what is already allowed by skills, class, and equipment/Paragon levels.
Diablo Immortal
In Diablo Immortal, the default Critical Hit Chance is 0%, and that of Critical Hit Damage is 100%. The amount written in the player stat is the bonus Chance and Damage on the default values. Monsters can also inflict crits in Diablo Immortal.
Development
Originally, each Critical Hit was supposed to cause a certain Crowd Control effect in addition to increased damage, such as Freeze for Cold attacks, or Silence for Arcane.