Damage

Character Damage
A Character's damage is the main factor all other damage scales off.

A multiplier is built and added together: This multiplier is applied to the character's base damage plus their level's damage resulting in the character's damage.
 * 1) +10% for each instance of BoostDamage the character has.
 * 2) -5% for each beetlejuice debuff. Presumed to be the flying bugs from Beetle Queen.
 * 3) +100% if the character is the Aurelionite
 * 4) The multiplier from the item Shaped Glass

Hit Damage
Each hit has damage info. This is scaled (possibly indirectly) from the character's damage. It holds the following properties: the attacker, the damage, if it crit, the damage type, the Proc Coefficient, the Proc chain, (position and force for knockback related calculations, the damagecolor and if the damage was rejected for displaying the damage). Upon hitting an enemy, the following things are done in order: the enemy applies the damage to themselves, the game checks if on hit items need to trigger, and the game checks if the attack needs to explode.

Receiving Damage
Note that this is both true for players and enemies. The game begins by creating a copy of the incoming damage amount, let's call this 'amount', whereas we'll call the old damage 'original amount'. If the character has succeeded the roll for Tougher Times, has just spawned in, or is otherwise invincible, set the damage rejected flag and stop applying any further damage. If the attacker has crowbars and the character is above 90% from their maximum combined health, multiply amount by (1.2+0.3*crowbars). If the attacker has Armor-Piercing Rounds and the character is a boss, multiply amount by (1.2+0.1*APR). If the hit was a crit, multiply amount by 2. If the damage doesn't bypass Armor (such as damage from a Shrine of Blood), apply the armor reduction/increase to amount. This can't reduce the amount to less than 1. If the character is a player and amount is bigger than 90% of the character's combined health, reduce the amount to 90% of the character's combined health instead. If applicable, apply certain slows to the character. If the character holds a Brittle Crown, take away money equal to the maximum between original amount*Crowns and Crowns*Money*(combined max health/amount). If this is fall damage, reduce amount to not take the character below 1 health, even if this means dealing 0 damage. Then finally, apply amount to shield first, and the rest to the health. And to end it, roll for the Old War Stealthkit with the original amount.

Damage for Procs
All damage that originates from a Proc doesn't straight up apply its damage coefficient to the hit, but rather takes the minimum between the  and the

Critical Strike
All Survivors have a base of 1% critical chance. Upon Critical strike, damage dealt is twice the amount of a normal attack.

One-shot Protection
A single hit taken can not deal more than  damage. This is checked after damage-reducing effects such as armor are applied.

Trivia

 * If you enable Damage Number in Gameplay Settings, the damage will be displayed after rounding to the nearest integer.