Talk:Tiamat/@comment-208.174.57.186-20121208150822/@comment-2177165-20121210012243

Devastating Blow is an on-hit effect that adds magic damage on top of the regular autoattack damage. Cleave is another on-hit effect. Both would be applied to the autoattack, but since Devastating Blow does not add to Attack Damage, no extra damage is added to the Cleave damage from Devastating Blow. It's likely that, due to software encapsulation, neither of them have any sort of communication with the other whatsoever, so they don't know of each other's existance.