Viashino Cutthroat

Five power with haste for four mana is a real beating, and the forced return is the price you pay for it: the body comes down swinging and goes back to your hand at the beginning of the end step, so you keep the discount only if you cash in the damage before the turn closes. That makes it a recurring threat priced like it lives on the stack rather than the battlefield, a creature that exists only during your own combat and vanishes before the opponent ever gets a turn with it on the table. Crucially, the return is owner's-hand, not sacrifice, so as long as it survives your turn it dodges sorcery-speed removal pointed at a creature sitting around between turns and replays clean the following turn for full retail. There is a hidden floor to the loop, though: the bounce only triggers if the Cutthroat is still on the battlefield at the end step, so trading it away in combat sends it to the graveyard like anything else, with no replay. The design therefore favors effects that trigger on attack or on a creature entering, since it can pay that entrance toll once per cycle without ever leaving a corpse for the opponent to plan around. It is a recurring Ball Lightning that gets to keep its card: the same one-turn swing, but the body comes home instead of dying, asking only that you find a use for the haste before the end step does the bookkeeping for you.