Kyle McGrath DBZ Dictionary Definition Edit

The player who activates a critical damage effect chooses to do one of the following: Capture an opponent's Dragon Ball, discard an opponent's Ally in play, or lower their opponent's anger by 1. A critical damage effect can always be used, even if your opponent has no Dragon Ball or Allies in play and has 0 anger.

Definition Specific Rulings and Clarifications Edit

Normally, Critical Damage Effects are used after an attack deals Critical Damage. Some card effects will allow you to use a Critical Damage Effect outside this window.

When you use a Critical Damage Effect, choose one of the following:

When choosing a Critical Damage effect, you may attempt to lower an opponent’s anger even if it is already zero, discard an Ally even if one is not in play, or capture a Dragon Ball even if one is not in play.[source]