Pythagron, Arctic Hydra

+2: Tap target creature an opponent controls. It doesn't untap during the opponent's untap step. You have hexproof.
-X: Pythagron, Arctic Hydra deals X damage to X targets. You gain X life.
-12: All your creatures have hexproof, lifelink, deathtouch and invincible until Pythagron, Arctic Hydra is discarded.