Oko, the Ringleader

In Commander, Oko, the Ringleader slots into any Simic or Temur shell that either spells-matters or wants a value engine that doesn't need protection to generate upside immediately. Powered eternal formats like Legacy and Vintage give him access to fast mana that gets him to six mana ahead of curve, but six-mana planeswalkers compete in crowded space there and he'll rarely be the best option in those shells. Modern and Pioneer are where he's most ambitious — he's playable but not dominant, requiring a deck built to protect him to get full value. Standard is likely his most accessible competitive home, where six mana is reachable without degenerate acceleration and the card-draw trigger compounds quickly in longer games.