Umbrage for Umbriss

Umbrage for Umbriss is a dungeon & raids achievement earned for defeating General Umbriss while he is affected with Modgud's Malice in Grim Batol on Heroic difficulty.

Strategy
The boss gains this buff when you kill a next to him, the buff lasts 20 seconds so you have to time it correctly. While affected, the boss deals 50% increased damage.