Arceus, the Original One

Arceus, the Original One can't be countered or
exiled from the stack.
If Arceus were to leave the battlefield due to any
cause other than itself, it doesn't instead. (Any
cause means due to a spell, ability or rule.)
Defender, flying
At the beginning of your upkeep, if you control
18 or more unown-type creatures, exile Arceus,
the Original One then return it transformed
under its owner's control.