Can be used even when there is no damage to prevent. It prevents the next damage (if any) from the source this turn.
04-10-2004
wotc
A source of damage is a permanent, a spell on the stack (including one that creates a permanent), or any object referred to by an object on the stack. A source doesn’t need to be capable of dealing damage to be a legal choice.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.
: The next time a blue source of your choice would deal damage to you this turn, prevent that damage.
