Lucither, Proudest of Angels

Indestructible, flying, renown 3 (When this
creature deals combat damage to a player, if it isn't renowned, put three +1/+1 counters on it and it
becomes renowned.)
At the beginning of your end step, if Lucither, Proudest of Angels are renowned, exile Lucither,
then return him to the battlefield transformed
under his owner's control.
"He asked all of us to bow down before you - to love
you more than Him. And I said.."