Kari, Unleashed Sinner

Hexproof, Shroud, Cursed Blessing 3(Whenever an instant or sorcery enters the battlefield each player loses 3 life and draws 3 cards)
Whenever you lose life for the first time each turn create an X/X Black Demon token where X is the amount of life you lost
Sacrifice half the creatures on the battlefield rounded up, you gain X life where X is the combined toughness of those creatures