The amount of life you gain is equal to the number chosen for X, not the amount of damage Consume Spirit deals (in case some of it is prevented).
01-10-2009
wotc
If the targeted permanent or player is an illegal target by the time Consume Spirit would resolve, the entire spell doesn’t resolve. You won’t gain any life.
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.