Barrier of Bones

A wall priced as a cantrip, where the 0/3 body is almost incidental to the trigger. For a single black mana, the surveil bins or keeps a card on the way down, and what you leave behind is a blocker that holds off early creatures while you set up. The design logic is to make graveyard-fueled decks pay nothing extra for their self-mill: a deck that wants cards in the bin (for delve, for reanimation, for threshold-style payoffs, for flashback fodder) gets the enabler stapled to a defensive speed bump, so a single slot does double duty without costing tempo. Defender is the cost here, not a drawback to engineer around; it caps the ceiling so the surveil-on-a-stick rate stays in check, and it means the body is honestly a blocker rather than a clock you might mistake it for. Surveil itself is the cleaner descendant of older self-mill tools that gave you no choice about what hit the graveyard: this one lets you keep a land or a needed spell on top, which makes it a smoothing tool as much as a filler-of-graveyards. It belongs to a quiet class of one-drops that do graveyard setup while asking for nothing in return, and its value tracks precisely how much a given build cares what sits in the yard.