Kroxa and Kunoros

In Commander, Kroxa and Kunoros is a legitimate threat: the end-step trigger hits all three opponents simultaneously, turning a single card into nine life and nine cards worth of pressure per full rotation. The graveyard-hate clause is relevant in nearly every pod, and shutting off flash disrupts a wide range of interaction. In competitive formats like Modern and Legacy, five mana is a steep ask against faster clocks, and the effect — while powerful in multiplayer — doesn't close games quickly enough to compete with the threats those formats support. Pioneer is similarly unkind; the mana cost puts it outside the efficient curve that format demands. Stick to Commander, where the multiplied trigger and incidental hate text are at their highest value.