https://wow.gamepedia.com/Attack_table
по 1% за каждый превышающий уровеньIf the game rolls a successful spell hit, the game then makes a second roll to decide if the ability is a critical strike or a regular hit.
Regardless of the attack type, players attacking higher-level targets have a reduced chance to crit relative to what's listed on their character sheet. For each level above the attacking character's level, players lose 1% crit. So, a level 87 character with 20% listed crit attacking a level 90 target only has 17% crit chance.
вне зависимости от типа атаки