Bash

Bash is a passive ability that gives a unit chance to deal bonus damage and stun its target on attack. The bash ability can be gained by abilities or the items Skull Basher, Abyssal Blade, and Monkey King Bar. Illusions are unable to bash.

Bash Stacking
Multiple sources of bash do not stack. The exception to this is for sources that grant a mini-bash lasting for much less than one second. Sources that do not stack will note it in their item description.

Melee Units with Bash
Melee units with bash deal bonus magical damage, but a physical stun. Thus the damage can be reduced by magic resistance and blocked by magic immunity, but the stun cannot be blocked by magic immunity.

Ranged Units with Bash
Ranged units with bash deal bonus physical damage, but a magical stun. Thus the damage can be reduced by armor, and the stun can be blocked by magic immunity.

Sources of Bash