Flowstone Overseer

The triple-red cost is the tell: this is a creature built to dominate a board it expects to share with other red permanents, an avatar of the mercenary-and-incursion attrition that gave its era its flavor. The repeatable +1/-1 is a toughness-shaving engine that pays two mana per activation to push a creature toward death from the bottom. Because the effect lasts only until end of turn, it is not a slow grind that whittles a board over multiple turns; it is a same-turn execution tool. Point it at one-toughness tokens and mana dorks and a single activation kills outright; point it at a wall of x/2 chump blockers and you can spend two activations apiece to clear a lane for its own 4/4 body, all on the turn you want the attack to land. The reason the rate holds is the resource cost: wiping a developed board takes a full turn's worth of mana you would otherwise spend developing your own, and the +1 power half rarely matters because raising power on a creature you are simultaneously killing is academic. It can also target your own creatures, pumping power for a swing or feeding a sacrifice line, though the math almost never favors it. This is transitional design: a repeatable red creature-removal engine from an era before the color settled fully into burn-to-the-face, when shrinking toughness by hand was still a sanctioned way for red to answer creatures.