Sebby, Destroyer of Worlds

Trample, haste, flying, indestructible, flash, lifelink, vigilance, double strike
When Sebby, Destroyer of Worlds enters the battlefield, exile all other permanents. Until the beginning of your next end step, you may cast those cards without paying their mana costs.
At the beginning of your upkeep, if you control fifteen or more creatures, you win the game.