+Firestorm (3)
As an additional cost to cast this spell, discard X cards.
Firestorm deals X damage to each of X targets.
Flying, trample
Cumulative upkeep (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Flying
If Firestorm Phoenix would die, return it to its owner's hand instead. Until that player's next turn, that player plays with that card revealed in their hand and can't play it.