Boon of Berserker +2

You grow stronger the lower your health falls. Whenever you cumulatively lose hit points equal to 1/2 of your hit point maximum, you gain a +2 bonus to your attack and damage rolls. 

Healed above 1/2 your hit points, or are out of initiative, please roll a Wisdom Saving throw to see if your flaw activates. DM decides Flaw.