Ezreal, Mystic Challenger

Haste
Whenever Ezreal enters the battlefield, you become the Monarch

When Ezreal etbs or attacks you may pay {x}{u}{r}. If you do, Ezreal deals X damage to any target. If that damage kills a creature, create a 1/1 red and blue elemental creature token with flying and become the Monarch.

At the beginning of your end step, if you are the Monarch, you may cast a nonland card from your graveyard for free. Exile it at the beginning of the next end step.