Reaver

From LegendWiki

Reaver [General]

Your bloodlust is intoxicating, spurring you on to claim more lives with every kill you make.
Prerequisites: Must not possess Livers Need Not Apply
Benefit: You gain a +1 bonus to attack rolls and Armor Class for every enemy whom you have killed in the current [Encounter]. This bonus can never exceed +4. Creatures who are more than three levels lower than you do not count.