Kellogg, Dangerous Mind

A mind-control payoff that funds itself, with the funding wired straight to the aggression. Each swing banks a Treasure whether or not the attack connects (the trigger fires on declaration, so a chump block still pays out), and five of those Treasures buy the opponent's best creature at sorcery speed. That coupling is what keeps a repeatable theft effect honest on a three-mana body: it takes five attacks, or outside Treasure production, before the first steal comes online. First strike and haste keep the clock ticking while the count climbs, so this is a red-black beater whose combat compounds into a bigger threat rather than a durdle hoarding artifacts. The theft carries a leash that permanent versions like Agent of Treachery never did: the stolen creature stays yours only for as long as you control Kellogg, so removing the Mercenary hands the creature straight back to its owner. That leash cuts both ways as a defense too; an opponent who exiles Kellogg breaks the control effect and reclaims their creature without you keeping a thing. The five-Treasure conversion is a real rate, and the sacrifice is a one-shot per activation rather than a persistent aura, which is why a build leaning on the theft wants to overproduce Treasures instead of trusting attacks alone. The loop is self-contained: attacking feeds the bank, the bank buys the opponent's best creature, and losing the engine unwinds every steal it paid for.