Magmaroth

A 5/5 for four mana in red is a body the color does not normally get to keep, so this one comes with a clock pointed at itself: it starts wasting away the moment you stop feeding it. The -1/-1 counter each upkeep is the leash, and the only way to slip it is to keep casting noncreature spells, one counter removed per cast. That makes the creature a tax meter on your own deck's composition. A spell-light board-stomping build watches it shrink to nothing in a few turns; a deck stuffed with burn, cantrips, and other noncreature spells can keep peeling counters as fast as the upkeep adds them and hold the body at full size. The catch is that the removal only ever clears existing counters: with none on the card, a noncreature spell does nothing for it, so you cannot run ahead and stockpile a cushion against future upkeeps. The two abilities race on the same track, and the card lives or dies by whether your hand keeps the spell side a step ahead. What makes the design unusual is how it inverts the normal relationship between a beater and its support spells: most fatties want you to spend your other cards protecting them, while this one wants you spending those cards anyway, on something else, and pays out the body as a side effect. The reward goes to the player who never intended to lean on creatures at all.