Target player sacrifices a creature, then gains life equal to that creature's toughness.
1/24/2013 Devour Flesh targets only a player. It doesn't target any creatures. The target player chooses which creature to sacrifice when the spell resolves. That player can sacrifice only a creature he or she controls.
1/24/2013 The amount of life gained is equal to the creature's toughness as it last existed on the battlefield.