Devour Flesh

Target player sacrifices a creature of their choice, then gains life equal to that creature's toughness.

Pioneer Masters

His twisted mind concluded that if he was what he ate, and he wanted to stay human, . . .

Gatecrash

Target player sacrifices a creature, then gains life equal to that creature's toughness.

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 they control.

The amount of life gained is equal to the creature’s toughness as it last existed on the battlefield.