Improved Fate of the Void is a heroic tier feat available to warlocks with a star pact and an Constitution or Charisma score of 13 or higher.

Normally, a warlock with a star pact gains a cumulative +1 bonus to any d20 roll during his or her next turn when an enemy under the warlock's Warlock's Curse is reduced to 0 hit points or fewer. A warlock with the Improved Fate of the Void feat gains an additional +1 bonus in this circumstance.[PH:198]

This is considered a mandatory choice, due to doubling the effect of the Warlock's main power.[Charop warlock]