To hit

Version 0.30: This article may not be up to date for the latest stable release of Crawl.

To hit (short for 'chance to hit') is the probability that an attack will hit a target. It is one of the two key factors in determining the success of an attack, the other being damage.

The to hit can be calculated for melee and ranged attacks, and is calculated differently for players and monsters. The largest factors for players are weapon (or unarmed) skill and fighting skill - with good training on both skills and decent dexterity, it should be rare to miss most targets.

To-hit vs EV

The higher an attack's to-hit is compared to the opponent's evasion, the more likely the attack is to land:

• 2.5% of the time, the attack misses regardless of the attack's to-hit or the defender's EV.
• 2.5% of the time, the attack hits regardless of the attack's to-hit or the defender's EV.
• Else, the game checks if 1d(to-hit + 1) - 1 ≥ 2d(2 * EV - 1)/2. If this equation is true, then the attack hits. Otherwise the attack misses.

Player To Hit (Melee and Ranged)

The player's to-hit in melee and ranged combat is determined by the following factors:

Base Value

• Start with 15 + dexterity/2 + a random roll between 0 and your fighting skill.

Weapons

• Add a random roll from 0 to your weapon skill (unarmed is considered a weapon skill here).
• Add the weapon's base accuracy; unarmed has +2, or +4 if you have claws.
• Add your weapon enchantment level and slaying bonuses.

Other modifiers

• If in wisp, fungus, pig, or non-vampire bat form, add random2(XL*100+100)/100 instead of using your weapon skill above.
• Subtract 5 for vertigo.
• If you have the eyeballs mutation, add 2*[eyeballs level]+1.

The Roll

• Take this total and roll a random number from 0 to (total - 1).

Post Roll

• Subtract 5 from wearing the Amulet of the Air.
• Subtract 5 if missing an eye (Ru sacrifice) or you are confused.
• Subtract 6 if you cannot see the target (invisibility).
• Add 2 + roll between 0 and 7 if the target is backlit (Corona, Sticky Flame, or under a halo).
• Subtract 2 + roll between 0 and 3 if the target is in umbra and you do not have night vision (from Dithmenos & Yredelemnul).
• The Confusing Touch spell grants +0 to +(DEX-1).
  • Being in the following forms grant bonuses:
    • Statue Form: 0 to +8
    • Dragon Form: 0 to +9
    • Lich form: 0 to +9
    • Ice Form: 0 to +9
    • Spider Form: 0 to +9
    • Bat Form: 0 to +11
    • Blade Hands: 0 to +11
    • Fungus Form: 0 to +9
    • Tree Form: 0 to +9
    • Wisp Form: 0 to +9

Monster To Hit (Melee)

A monster's to hit is calculated as follows:

Base Value

The base value is 18.

Hit Dice

Monsters with the Fighter class flag get a bonus of +(2.5 * HD). Other monsters get +(1.5 * HD). Decimals are rounded down.

Situational Modifiers

• An aquatic monster "using the terrain to its advantage" gets +5.
• A monster wielding a weapon receives that weapon's inherent and magical to hit modifiers.
• A confused monster gets -5.
• A monster attacking a backlit defender gets +2 to +9.
• A monster attacking an invisible target suffers a 35% penalty to its to hit number.

Monster To Hit (Ranged)

Ranged attacks ("beams", to use the game's internal terminology) have a to hit number, just like melee attacks do. This is modified as follows:

• If you are invisible and the attacker can't see invisible, the to hit number is halved.
• If you have Repel Missiles, the to hit number is reduced by a random number between 0 and 1/2 of its value (rounded down).