Endless Coffin

You may treat all instances of this card as though it was a graveyard in addition to it's other types. (It has all rules and concepts of a graveyard.)
At the beginning of your upkeep, sacrifice a creature to Endless Coffin. If you can't, sacrifice Endless Coffin.
Whenever a spell would target a card in Endless Coffin, replace all instances of the word 'target' with 'each'.