Shadow, Omnipotent One

Only cast this spell if Shadow, Lord of Butter is
in your graveyard.
{3}, {t}: Exile 5 cards from the top of your library.
You may cast 2 of these cards without paying their
mana cost.
The Slumber:This card enters the battlefield with
6 time counters on him. Remove 1 every turn that
he is on the battlefield. Once there are 0 Counters remaining, he sleeps for 3 turns in exile, then
return him to the battlefield.