Form of the Demon

Hexproof.
When Form of the Demon enters the battlefield your life total becomes 7.
At the beginning of your upkeep, deal 7 damage to target creature, if there are no creatures on the battlefield you lose 7 life instead.
Whenever a creature an opponent controls dies you lose 1 life and draw a card.
Sacrifice a non-demon creature: You gain 1 life.