A prevent ability keeps the uncompleted activation of an ability from ever completing.
How to PlayEdit
If an ability is prevented, its activation cannot begin. If an ability is prevented and its activation has already begun but it has not completed activation (i.e. it is a pending ability), the completion of the activation of the pending ability is skipped (i.e., it is no longer a pending ability even though it did not complete its activation). An ability can not be prevented if its activation has already completed.
All prevent abilities are ongoing. A prevent ability targets the abilities that they prevent. Prevent abilities are an exception to the rule that states targets must be declared when a card is activated because when a prevent ability is activated the cards it is intended to target are generally not valid targets. The targets of a prevent ability are targeted as they become valid targets. The delayed targeting nature of a prevent ability is what makes it ongoing. Once a card has been targeted by a prevent ability, the effect of preventing it happens instantaneously.
- Prevent abilities that have an unlimited number of targets last until the end of the phase in which they are used.
- Prevent abilities that have a limited number of targets last until the end of the phase in which they are used or until they reach their limit on number of targets (whichever comes first).
- Targets must be in play.
- Targets of a prevent ability that are known when the prevent is played must be declared according to the normal targeting rule.
- Abilities that are worded “negate all special abilities” (even if the ability includes an exception or is limited to all special abilities of a certain type, but does not “currently in battle”) are actually a combination of a prevent and a negate ability. They should be played as “negate all [specified set of abilities] in play and prevent all [specified set of abilities] for remainder of battle.”
- The phrases “No [card type] may,” “cannot,” and “may not” when not immediately followed by the word “be” indicate prevent abilities.