Glacial Fortress

In Commander, Glacial Fortress is the default budget dual for any Azorius or multicolor deck with a meaningful Plains and Islands count — it enters untapped nearly every game past turn two, and at bulk price there's no reason to skip it. In Modern and Pioneer, it sees play in white-blue control shells where the check-land condition is met by basic-heavy lists, though faster aggressive matchups punish any early tapped land and push those decks toward fetchland-shock configurations instead. Legacy and Vintage don't need Glacial Fortress given access to better options, but it's technically legal if you're building on a strict budget. Oathbreaker mirrors Commander's calculus exactly — two-color white-blue decks run it as a matter of course.