Cursed Fists

Upon selecting this feat, you choose your Charisma or Wisdom modifier for your save.

Whether tattooed or scarred, your fists now possess runic markings. These allow you to drain your opponent's vitality, feeding it to some other power depending on the nature of the runes. 

When you hit with an unarmed attack, your target must make a Con, Str, or Dex Saving Throw chosen by the target with a DC = Cha or Wis mod + 11. On a success, the runes do not activate. On a failure, the target's chosen Ability Score lowers by 2. This decrease lasts until the beginning of your next turn.