Festerleech

A one-drop that self-mills is usually a graveyard enabler first and a creature second, but the ordering here is inverted: the mill only fires on combat damage, which means the card has to survive contact and connect before it fills anything. That turns the pump into the whole plan rather than a bonus. Spending an activation each turn to swing as a 3/3 (and then, next turn, again) is how it clears the ground it needs to clear, and every hit that lands buries two more cards. The two engines feed each other on the same axis: the leech grows to get through, and getting through is what mills. It is a self-milling attacker built for decks that want their graveyard stocked as a consequence of dealing damage, not as a turn-one dump. The once-per-turn clause on the pump is the restriction that keeps it from spiraling into a real threat: no double-activation blowouts, no surprise ten-power leech out of a full grip. What it asks for is a board state where a small evasive-or-unblocked body keeps connecting turn after turn, which is a narrower ask than a straightforward mill spell but a more repeatable one. Where a fill-the-yard payoff pays off, this is the kind of body that does the filling by attrition.