is a passive ability that gives a unit a chance to deal bonus damage and stun
its target on attack.
Multiple sources of Bash will stack, with the longest-duration stun overshadowing the others, but heroes with Bash abilities are generally prevented from purchasing Skull Basher and Abyssal Blade. Illusions cannot Bash, but the stun animation will still play over the affected hero.
A bash has two components: the damage and the stun. Both are governed by the rules of damage types in their interaction with magic immunity.
For example, Time Lock deals magical damage with a physical stun. The stun will penetrate magic immunity but the damage will not. Headshot on the other hand deals physical damage with a magical stun; the damage will penetrate magic immunity but the stun will not.
Bashes that deal physical damage add their damage directly to a hero's physical attack, and will therefore grant lifesteal and be multiplied by critical strike.
Slardar's Bash, Faceless Void's Time Lock, Sniper's Headshot and Roshan's Bash are subject to pseudo-random distribution.
 Sources of Bash