Rule 438.1.b

Prevent appears in statements that define an amount of damage and the source of the damage it will affect, as well as the timespan it will be relevant for.

• 438.1.b.1 Prevent actions are usually formatted as “Prevent the next X [source] damage that would be dealt to a [unit] this turn.”
• 438.1.b.2 Prevent will always apply to the next damage that would be dealt to a unit affected by the Prevent action.

Official Core Rules