Grudge Keeper

You have an overpowering need for vengeance and have difficulty letting go of grudges.
Effect: if you are damaged in combat, you suffer a -2 penalty on attacks rolls, skill checks, saving throws, and ability checks until you damage the foe who caused you harm. This penalty does not apply if you cannot discern the source of the damage. This penalty disappears when the combat ends.
Suggested Class/Race: Dwarf
Source: Dragon Magazine #328 (Nobody’s Perfect – New Flaws for Nonhumans)