Soulstinger

A 4/5 body for four mana reads as a beater until you read the tax: it cannot arrive without dropping two -1/-1 counters onto a creature you already control, and the entrance cost is the whole design. This is a -1/-1 counter battery wearing a Scorpion Demon's frame, and the payoff lives in the death trigger, which redistributes a counter to a target for each one the demon is carrying when it dies. Park those two counters on the demon itself rather than on a fragile ally, and you have loaded a delayed removal spell into a creature that also blocks well: sacrifice it or trade it in combat, and it exports both counters to shrink something small out of existence or hobble something large. Cost and kill run through the same mechanic, so the interesting decisions sit upstream, before the demon ever dies. Do you route the enters trigger onto a body that welcomes the counters (an undying creature, whose -1/-1 counters cancel its +1/+1 counters and reset the ability; a token you were fine to lose) and keep the demon clean? Or do you deliberately overload the demon, feeding it counters so its death payload lands bigger? A demon that survives combat untouched leaves quietly; one that has absorbed and stored a full counter count leaves with a removal spell stapled to it. The wound you inflict on your own board is the down payment on the one you get to inflict later.