User blog comment:Willbachbakal/(CB1) Hannibal, the Dread Vanguard/@comment-533780-20150326154812/@comment-7709681-20150326163004

You're misunderstanding War Engine. He stores the total amount of pre-mitigation damage he receives, up to a cap equal to 40% of his heallth. Once he reaches the cap begins a 3s timer visible to all players, once the timer ends he deals magic damage equal to % of it's content (or % of his max. health) and all units damaged by  seconds.