Minion of Tevesh Szat
The repeatable +3/-2 reads as a combat boost, but the -2 is where the work happens: any creature with two or fewer toughness dies the instant the demon taps, one X/2 cleared per turn. The +3 is flavorful dressing that lets a removal engine masquerade as a monstrous gift to whichever beast it targets. Because the kill demands a tap, the body and the activation never happen on the same turn; each turn forces a choice between swinging with the 4/4 or sawing down a target, never both. The upkeep tax runs on a separate track entirely: each of your upkeeps the demon asks for double-black, and any turn you cannot spare it, it deals 2 damage to you. Note that this is damage, not a sacrifice, and note too that the tap ability costs no mana of its own. Skipping the payment never stops the saw; it just bleeds you. The minion is never going anywhere on its own, so the tax cannot be a downside you grow out of. It compounds against your life total rather than against the engine: the removal keeps firing whether or not you feed the upkeep, but every turn you withhold the double-black is 2 life gone, and every black you do spend on it is black unavailable elsewhere. This is high-friction black where the drawback sits beside the payoff instead of gating it: the demon will keep cutting their creatures, and the only thing left to cut, if you starve it, is you.

