What doesn't kill you makes you stronger. This is the creed of all berserkers and you know it well.
when a creature deals damage to you, you can use that pain to fuel your combat prowess. On your next turn, as a bonus action, you can deal additional damage on your next successful melee attack equal to half the total damage that creature would have delt. For example, if an opponent rolls a 12 on their greatsword strike and adds 4 due to their Strength modifier, you can deal 8 additional damage with this feature, regardless of resistances. This damage can only apply to the target that dealt that damage to you. You can use this feature a number of times equal to your Constitution modifier and you regain all expanded uses once you finish a long rest.