Phiron, Prinordial Flame

When Phiron, Primordial Flame enters the battlefield, it deals X damage to each creature,
where X is the amount of {r} mana you used to
cast it.
Flash, Haste
Phiron can only be destroyed in combat. When
it is, it deals 10 damage to each creature and
planeswalker, then shuffle it into your library.