Editing Critical hit

[[File:Critical hit.png|thumb|A critical hit with a [[shortsword]].]]'''Critical hits''' occur when a creature [[Dice roll|rolls a natural 20]] on an [[attack roll]]. Critical hits automatically land regardless of the target's [[AC|armour class]], and the attacker also rolls twice the normal number of dice to determine damage dealt.

While initially a mechanic subject purely to the whims of luck, a number of features, abilities, and items allow the player to manipulate the odds of scoring a critical hit. Combined with effects that make critical hits themselves stronger, building around critical hits can be a valid strategic option.
==Mechanics==
Any ability that uses an attack roll, including spell attacks, is capable of landing critical hits. Any dice that are rolled for damage, including additional dice such as those from [[Divine Smite|smites]] or [[Battle Master|combat manoeuvres]], are rolled twice. Abilities with multiple attack rolls like {{SAI|Slashing Flourish (Ranged)|Slashing Flourish}} or {{SAI|Scorching Ray}} can have multiple critical hits, with each attack rolling independently of one another.

Flat modifiers and bonuses to damage – including the creature's relevant [[ability score modifier]] and [[proficiency bonus]] – are not doubled.
==Reducing critical threshold==
Some feats, passive features, and items reduce the critical hit threshold by 1, allowing the creature to land critical hits by rolling either 19 or 20 on attack rolls. Multiple sources of this effect stack, allowing the critical hit threshold to go even lower than 19.
===Equipment===
====Weapons====
*{{MdRarityItem|Unseen Menace}} ''(while the weapon is {{Cond|Invisible Weapon|invisible}})''
*{{MdRarityItem|Bloodthirst}} → [[Improved Critical]]
*{{MdRarityItem|The Dead Shot}} → [[Improved Critical]]<ref>Both [[The Dead Shot]] and [[Bloodthirst]] grant the same passive, but are still able to stack.</ref>
*{{MdRarityItem|Knife of the Undermountain King}} → [[Organ Rearranger]]
*{{MdRarityItem|Duellist's Prerogative}} → [[Elegant Duellist]] ''(while off-hand is empty)''
====Cloaks====
*{{MdRarityItem|Shade-Slayer Cloak}} → [[Stealthy Critical]] ''(while {{SAI|Hide|Hiding}})''
====Armour and headgear====
*{{MdRarityItem|Covert Cowl}} → [[Covert Critical]] ''(while [[Obscured]])''
*{{MdRarityItem|Dark Justiciar Helmet}} → [[Covert Critical]] ''(while [[Obscured]])''
*{{MdRarityItem|Sarevok's Horned Helmet}} → [[Deathbringer's Sight]]
===Conditions===
*{{SAI|A Most Bloody Inheritance (Condition)|A Most Bloody Inheritance|w=30}} - Critical threshold reduced by 2, available only in the [[The Dark Urge]] origin.
===Consumables===
*{{MdRarityItem|Elixir of Viciousness}}
===Class features===
*{{SAI|Improved Critical Hit|w=30}} - Level 3 passive for the [[Champion]] [[Fighter]] subclass.
===Feats===
*{{SAI|Spell Sniper|w=30}} - Spell attacks only.
===Illithid Powers===
*{{SAI|Fierce Perilous Stakes|w=30}} - Target's critical threshold is reduced by 5, but it is also vulnerable to all damage.
==Maximising critical hit value==
===Increasing likelihood of critical hits===
Any effect that triggers a re-roll of an attack die will increase the likelihood of landing a critical hit. Attacking with [[Advantage]] almost doubles the likelihood of rolling a critical.<ref>https://statmodeling.stat.columbia.edu/2014/07/12/dnd-5e-advantage-disadvantage-probability/</ref> Features that allow for situational rerolls, like {{Sai|Halfling Luck}}, similarly increase the odds. Reducing the critical threshold increases chances of scoring a critical hit accordingly; taking into account advantage and multiple attacks, the odds of hitting at least one critical with a character in one round of combat are as follows:<ref>[[Guide:Book's Guide to Crits]]</ref>
{| class="wikitable"
!Critical Hit Threshold
!Chance without Advantage
!Chance with Advantage
!Two attacks with advantage
|-
|20
|5%
|9.75%
|18.55%
|-
|19
|10%
|19%
|34.39%
|-
|18
|15%
|27.75%
|47.8%
|-
|17
|20%
|36%
|59.04%
|-
|16
|25%
|43.75%
|68.36%
|-
|15
|30%
|51%
|75.99%
|-
|14
|35%
|57.75%
|82.15%
|}
===Additional effects on critical hit===
On the other side of things, some effects add add additional value to critical hits when they occur. These include:
*{{SAI|Brutal Critical}} and {{SAI|Savage Attacks}} add an extra damage die to the damage of the attack, i.e. an attack dealing {{DamageText|1d10|Bludgeoning}} will critically deal {{DamageText|2d10 + 1d10|Bludgeoning}}. Additional damage dice, like those from battle manoeuvres, are not subject to this additive bonus, with the exception of {{SAI|Divine Smite}}.
*Effects that reroll damage rolls will see greater benefit on critical hits, since the raw number of damage rolls increases:
**{{SAI|Savage Attacker}} rerolls all damage die twice.
**{{SAI|Great Weapon Fighting}} rerolls damage die for two-handed melee weapons, when rolling a 1 or 2.
*Effects that provide a unique bonus when a critical hit occurs:
**{{SAI|Paralysing Critical}} paralyzes a target on critical hit, once per long rest.
**{{SAI|Mortal Reminder}} possibly frightens enemies on critical hit.
**{{SAI|Great Weapon Master: Bonus Attack}} enables an attack using a bonus action, after a critical hit.
**{{RarityItem|Spellthief}} restores a level 1 spell slot on critical hit.
**{{RarityItem|Dolor Amarus}}, {{RarityItem|Vicious Battleaxe}}, and {{RarityItem|Vicious Shortbow}} add a flat damage boost to critical hits.
**{{RarityItem|Sword of Life Stealing}} adds a flat damage boost to critical hits and adds [[Temporary Hit Points|temporary hit points]].
**{{RarityItem|Intransigent Warhammer}} knocks creatures prone in a radius on critical hit.
**{{RarityItem|Craterflesh Gloves}} adds {{DamageText|1d6|Force}} to critical hits, itself doubled as it is adding an additional damage die.
**{{RarityItem|Blightbringer}} inflicts {{Cond|Slowed}} on critical hit.
**{{RarityItem|Clown Hammer}} inflicts {{Cond|Hideous Laughter}} on both target and user on critical hit.
===Guaranteed critical hits===
There are also several ways to guarantee a critical hit.
*Melee-range attacks against{{Cond|Paralysed}} or {{Cond|Sleeping}} targets
**Includes {{SAI|Hold Person}}, {{SAI|Hold Monster}}, and {{SAI|Clench of the North Wind}}
*{{SAI|Luck of the Far Realms|w=30}} - Once per [[Long Rest]]
*{{MdRarityItem|Killer's Sweetheart}} after killing a creature, once per [[Long Rest]] after killing a creature
*{{SAI|Assassinate:_Ambush|Assassinate:Ambush|w=30}} against {{Cond|Surprised}} creatures
*{{SAI|Scarlet Saturation|w=30}} once per [[Long Rest]] after consuming the +3 bonus from {{Cond|Scarlet Remittance +3}}
*After applying {{Cond|Exposing Bite}}, on the next attack made from within melee range
*Next attack made with a weapon enchanted by {{SAI|Wild Magic: Enchant Weapons}}

==Negating critical hits==
Some equipment prevent attackers from landing critical hits on the wearer when worn. When a natural 20 is rolled on an attack roll against the wearer, the roll is simply treated as a 20 while still being affected by the wearer's [[Armour Class|armour class]]. With a high enough armour class while wearing equipment that prevents critical hits from being landed, it is possible to always be missed by attack rolls, even if a natural 20 is rolled.
===Equipment===
====Armour and headgear====
*{{MdRarityItem|Adamantine Scale Mail}}
*{{MdRarityItem|Adamantine Splint Armour}}
*{{MdRarityItem|Grymskull Helm}}
*{{MdRarityItem|Helldusk Helmet}}
*{{MdRarityItem|Helm of Balduran}}
====Shields====
*{{MdRarityItem|Adamantine Shield}}

==Footnotes==
<references />

==See also==
*[[Advantage#Math|Advantage]] - For more on the calculations behind critical successes, misses, and advantage.
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