With every enemy life you take, you become increasingly dangerous and difficult to stop. During the duration of the spell, you gain a cumulative +1 luck bonus on melee attack rolls, melee weapon damage rolls, Strength checks, and Strength-based skill checks as well as DR 2/— each time you reduce a qualifying opponent to 0 or few hit points (maximum +5 bonus and DR 10/—) with a melee attack. A qualifying opponent has a number of Hit Dice equal to or greater than your Hit Dice –4.