Living Bag of Holding

{1}{t}: Exile the top card of your library under
Living Bag of Holding.
{3}: You may cast a spell exiled with Living Bag of Holding. The spell's cost is reduced by x, where x
is the number of cards exiled under Living Bag of
Holding.
{5}: Living Bag of Holding becomes an Artifact
Creature Demon with indestructible and power and toughness equal to the number of cards exiled under Living Bag of Holding.