Critical hit

Critical hits (or crits) are a combat mechanic that guarantee a successful hit with a small chance.

Base Mechanics

To-hit rolls use a roll on a 1d20 die. If the die rolls 20, before factoring in the attacker's Agility modifier and other changes to the roll, the attack will be a critical hit. This means that the chance to get a critical hit will always be 5%, unless a creature has skills or equipment that explicitly change it.

Critical hits dealt with melee weapons hit regardless of DV and gain a +1 bonus to PV. In addition, if the attacker is the player (including the player in the body of another creature), the attack will have one extra penetration, even if there would otherwise have been none. Melee critical hits also cause a splatter of blood, sap, or oil, depending on the lifeblood of the target, though this does not cause any additional damage and is not the same as a bleeding effect.

Critical hits with missile weapons increase the PV of the shot by 2. They do not always hit, meaning that it's possible to always dodge missile attacks from specific creatures when DV is at least 20 higher than the creatures' to-hit modifier. In addition, a missile weapon's attack roll is only made once the projectile reaches the tile of the target, meaning that angular variance will result in a practical chance of hitting the intended target of less than 5%, except in situations with very low angular variance and/or a short distance from the attacker to the target.

Modifiers

• Melee weapon types each have a special effect when dealing critical hits. These effects apply even if the attacker does not have the related weapon skill:
  • Short Blades will cause bleeding, dealing 0-1 damage per turn to the target
  • Axes will cleave armor, reducing the AV of the target
  • Cudgels daze enemies, lowering their Agility, intelligence, and move speed, and setting them up for a potential stun if they are critical hit a second time.
  • Long Blades get a +2 bonus to penetration (even if this would exceed the weapon's penetration cap)
• The tinkering mod masterwork reduces the 1d20 roll needed to achieve a critical hit by 1. With no other modifiers, this enables scoring a critical hit on a roll of 19 or 20, for a total critical hit chance of 10%.
• Weak Spotter also reduces the 1d20 roll needed to achieve a critical hit by 1. With no other modifiers, this enables scoring a critical hit on a roll of 19 or 20, for a total critical hit chance of 10%. When combined with masterwork, this results in a total critical hit chance of 15%.
• precision nanon fingers reduce the 1d20 roll needed to achieve a critical hit by 2. With no other modifiers, this enables scoring a critical hit on a roll of 18, 19, or 20, for a total critical hit chance of 15%. Multiple pairs stack additively (for example, two pairs reduce the roll needed by 4, for a total critical hit chance of 25%). This bonus can also be combined additively with the bonus from masterwork or Weak Spotter.
• Beacon Fire requires the target to be flaming, luminous or phosphorescent, but guarantees a critical hit with rifles or bows when used
• Dead Shot doubles the PV bonus of critical hits made with pistols from +2 PV to +4 PV
• Ruin of House Isner receives an additional +4 to its PV on critical hits, and automatically hits critically on the last shot of a full magazine

References

This information is reliable as of patch 2.0.201.70.