Enlightened Aethermage

Flash (You may cast this spell any time you could cast
an instant.)
Whenever Enlightened Aethermage or another creature enters the battlefield under your control
you may exile up to one target creature. If you do, return that card to the battlefield under its owner's control at the beginning of the next end step.
Whenever a creature you control leaves the battlefield, if it didn't die, creatures you control
get +1/+1 until the end of turn.