Tiamat's Bitter Vengeance is a heroic tier feat from the Book of Vile Darkness supplement.
Any wrong done to you fills you with anger, driving you to do the same to the one who crossed you.
Prerequisite: Channel Divinity class feature, must worship Tiamat
Benefit: You gain the power Tiamat's Bitter Vengeance power.[BoVD:32]
Tiamat’s Bitter Vengeance
Feat utility
You can channel Tiamat’s wrath, gaining the revenge she de-mands above all else.
Personal
Special: You can use only one channel divinity power per encounter.
Trigger: An enemy hits you with an attack.
Effect: You shift up to 3 squares. Until the end of your next turn, each time you or an ally hits the triggering enemy, it takes 2 extra damage. Level 11: 4 extra damage. Level 21: 6 extra damage.