Cellar Door
Mill from the wrong end. Every other graveyard-filler reaches off the top of the library, where both players can see what is going; this one reaches under the deck, to the one card neither player has any read on. That blindness is the whole conceit: you are not stripping a known threat or fueling a specific delve count, you are gambling that the random bottom card is a creature so the Zombie token shows up. The math is deliberately bad. Three mana every activation, one card from a part of the library nobody is tracking, and a coin-flip-ish chance at a single 2/2 that arrives one body at a time. It is a token engine pretending to be a mill artifact, or a mill artifact pretending to be a token engine, and it is not efficient at either. What it is, instead, is a flavor object that happens to have rules text: a literal door in the cellar that you crank open turn after turn, and sometimes something dead walks out. The design belongs to a small family of cards built more to evoke a horror beat than to win a game, where the activation cost sits high enough that the payoff reads as a bonus rather than a plan. The bottom-of-library hook has rarely been revisited, which is its own quiet verdict on how much the table wants to interact with a zone it cannot see.

