Zil'Shen, Cinder of Riav

Flying
Zil'Shen, Cinder of Riav enters the battlefield with a number of ember counters on it equal to the amount of mana spent to cast it.
Remove an ember counter from Zil'Shen, add {u} or {r} to your mana pool. Spend this mana only to cast instants or sorceries.
He waits for the titans of yore to return.