Nissa, Steward of Elements

In Commander, Nissa, Steward of Elements is a role-player rather than a flagship threat — she earns her slot in Simic decks that manipulate the top of the library and want a repeatable, low-overhead way to cheat permanents into play. In Pioneer and Modern, she sees fringe play at best; the X cost means you're rarely jamming her on curve, and both formats move too fast to let her zero ability generate real advantage without significant setup. Legacy and Vintage have access to better planeswalkers and faster mana acceleration, so Nissa, Steward of Elements mostly doesn't register there. Oathbreaker is where she genuinely thrives as a signature spell or supporting piece, since the lower player count and streamlined game length let her scry-and-deploy loop close games before opponents stabilize.