Shallow Grave was not playable, I could not cast it despite having a Ravenous Kraken on board. I drew the Shallow Grave with Scourge Supplies on a turn I had Thaddius, Monstrosity on the board on an “all even-cost cards” turn. After Thaddius and the Kraken died, I was still unable to play the Shallow Grave the next turn with a Flesh Behemoth on the board