Gnawing Vermin

Two triggers on the cheapest possible body, and they pull in opposite directions: one wants the rat to arrive, the other wants it gone. The enter trigger mills two, a modest bit of graveyard-filler that only earns its keep in a shell already leaning on its bin, and the fact that you can point it at yourself is the tell that self-mill sat on the whiteboard next to the attrition plan. What sharpens the card is the death half. When the rat dies, a creature you don't control gets -1/-1 until end of turn: chumping into a bigger attacker still shrinks it on the way out, and blocking a lone 1/1 stops being an even trade because you can hand the penalty to whatever else the opponent already has on the board. That is the constraint worth naming: the shrink resolves the moment the rat dies and needs a target already in play, so it clears something present, not something the opponent has yet to commit. Where the card wants to live is a black sacrifice deck, because there the death payoff stops being incidental combat math and becomes something to farm on schedule: feed it to an outlet, mill your own toolbox, and drop a -1/-1 exactly when you need a token wiped or a blocker softened. On its own it is a small piece of attrition. Wired into a deck built to make creatures leave the battlefield, both halves finally start pulling the same way.