Harvester of Misery

The design trick is that the -2/-2 sweep and the discard ability are the same effect at two speeds, and each copy typically pays out once. Cast for five, it wipes the small board on the way in and leaves a 5/4 with menace to finish the job. But if the game never opens that window, the card is not dead weight in hand: pitch it for a mana and a black to shrink one attacker or blocker at instant speed, and you have converted a stranded fatty into a modest removal spell. That mutual exclusivity is the balancing act. A 5/4 menace body is worth a card on its own, so the enters-the-battlefield sweep and the discard removal are two options from one slot, and you commit to one when you decide whether to cast it or ditch it: the aggressive line or the flexible one, usually not both. The sweep hits other creatures, so it never touches its own toughness, and the menace it keeps means the body left standing is genuinely hard to gang-block once the smaller creatures have already died. It sits in a long line of black creatures that carry their own removal (the Nekrataal school of the two-for-one body), but where those trade an attached spell for stats, this one hands you a mode switch instead: keep it for the beats, or spend it as a spell when the beats never come.