Perfect Healing Art

If a Creature you control would die, you may pay 4
life, prevent that Creature from dying this turn.
If you would take battle damage, you may sacrifice a
Creature instead. If that damage would reduce your
life total to 0 or below, you must sacrifice a nontoken
Creature to prevent that damage if able.
As long as you control a nontoken Creature, you
cannot lose the game.

"My mortality is no one's business but my own!"