Creepy Puppeteer

A 4/3 haste beater with a rider that reads like a puzzle: swing with this and exactly one other creature, and you may rewrite that partner's base power and toughness to a matching 4/3 for the turn. Because it sets base stats rather than adding to them, the effect is almost entirely an upsizing tool: a small attacker that connected earlier suddenly hits for four, which is why the trigger wears "you may" as a valve rather than a mandate. Point it at a genuinely large creature and you would be shrinking your own board, so there the option just goes unused; nothing is ever forced onto a body it would weaken. The "exactly one other creature" clause is the balancing pin. It punishes a wide swarm and rewards a tight two-attacker board, and it sidesteps targeting entirely: there is one other attacker or the trigger never fires. Haste lets it enter that math the turn it lands, so a fresh body can immediately drag a stalled one-drop up to lethal size or bulldoze a stalled race. This belongs to the family of red beaters that carry a combat rider instead of raw evasion, asking the pilot to sequence attacks with an eye on what the puppet-string can lift. The payoff never explodes; the interest is reading each combat and deciding whether that 4/3 template is worth handing to the creature swinging beside it.