Greven, Predator Captain
Legendary Creature — Phyrexian Human Warrior, {3}{B}{R}
Oracle Text
Menace
Greven gets +X/+0, where X is the amount of life you've lost this turn.
Whenever Greven attacks, you may sacrifice another creature. If you do, you draw cards equal to that creature's power and you lose life equal to that creature's toughness.