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Critical hit
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 smites or combat manoeuvres, are rolled twice. Abilities with multiple attack rolls like 
or 
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. Creatures whose attacks deal a flat amount of damage rather than a die roll, such as Familiars, can roll critical hits but do not deal extra damage on them.
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
Bloodthirst → Improved Critical
Duellist's Prerogative → Elegant Duellist (while off-hand is empty)
Knife of the Undermountain King → Organ Rearranger
The Dead Shot → Improved Critical[1]
Unseen Menace (while the weapon is 
)
Cloaks
Shade-Slayer Cloak → Stealthy Critical (while 
)
Armour and headgear
Covert Cowl → Covert Critical (while Obscured)
Dark Justiciar Helmet → Covert Critical (while Obscured)
Sarevok's Horned Helmet → Deathbringer's Sight
Conditions
- Critical threshold reduced by 2, available only in the The Dark Urge origin.
Consumables
Elixir of Viciousness - Reduces the number needed to roll a Critical Hit by 1.
Class features
Feats
- Spell attacks only.
Illithid Powers
- 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.[2] Features that allow for situational rerolls, like 
, 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:[3]
| Critical Hit Threshold | Chance without Advantage | Chance with Advantage | Two attacks with advantage | Three attacks
(two main+off-hand) with advantage |
|---|---|---|---|---|
| 20 | 5% | 9.75% | 18.55% | 26.49% |
| 19 | 10% | 19% | 34.39% | 46.86% |
| 18 | 15% | 27.75% | 47.8% | 62.29% |
| 17 | 20% | 36% | 59.04% | 73.79% |
| 16 | 25% | 43.75% | 68.36% | 82.20% |
| 15 | 30% | 51% | 75.99% | 88.24% |
| 14 | 35% | 57.75% | 82.15% | 92.46% |
Additional effects on critical hit
On the other side of things, some effects add add additional value to critical hits when they occur.
Passives
and 
add an extra damage die to the damage of the attack, i.e. an attack dealing 1d10
Bludgeoning will critically deal 2d10 + 1d10Bludgeoning. Additional damage dice, like those from battle manoeuvres, are not subject to this additive bonus, with the exception of 
.
rerolls damage die for two-handed melee weapons, when rolling a 1 or 2.
enables an attack using a bonus action, after a critical hit.
possibly frightens enemies on critical hit.
rerolls all damage die twice.
Actions and spells
paralyzes a target on critical hit, once per long rest.
Equipment
Blightbringer inflicts 
on critical hit.
Clown Hammer inflicts 
on both target and user on critical hit.
Craterflesh Gloves adds 1d6
Force to critical hits, itself doubled as it is adding an additional damage die.
Dolor Amarus adds a flat damage boost of 7 to critical hits.
Intransigent Warhammer knocks creatures prone in a radius on critical hit.
Spellthief restores a level 1 spell slot on critical hit.
Sword of Life Stealing adds a flat damage boost to critical hits and adds temporary hit points.
Vicious Battleaxe adds a flat damage boost of 7 to critical hits.- Vicious Shortbow adds a flat damage boost of 7 to critical hits.
Guaranteed critical hits
There are also several ways to guarantee a critical hit.
against 
creatures
, on the next attack made from within melee range
Killer's Sweetheart once per Long Rest after killing a creature
once per Long Rest- Melee-range attacks against
or 
targets
once per Long Rest after consuming the +3 bonus from 
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. 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
Shields
Notes
- ↑ Both The Dead Shot and Bloodthirst grant the same passive, but are still able to stack.
- ↑ https://statmodeling.stat.columbia.edu/2014/07/12/dnd-5e-advantage-disadvantage-probability/
- ↑ Guide:Book's Guide to Crits
See also
- Advantage - For more on the calculations behind critical successes, misses, and advantage.
