Ostoah, Lord of Verdure

Flying, trample
Whenever another creature enters the battlefield
under your control, exile the top card of your
library. If it's a nonland card, you may cast it this
turn.
When Ostoah, Lord of Verdure dies, exile it
instead. You get an emblem that says "Creatures
you control get +1/+0 for each card you own in
exile."