My'vaak, the Ghost Hunter

Penance Stare:
When My'vaak enters the battlefield, destroy all attacking/defending creatures, gain Indestructible.
Spirit of Vengeance:
Pay {r}{r}{r}{r}{r}{r}{r}{r}{r}{r}, destroy all creatures/Planeswalkers under your opponent's control, if your opponent's has more health than you, win the game immediately.
Additional creature type: Planeswalker
When Spirit of Vengeance is activated, My'vaak transforms to a Planeswalker.