https://oathbreakermtg.org/banned-list/


Rather than choosing a legendary creature as a commander, players select a planeswalker as their Oathbreaker, and an instant or sorcery as that Oathbreaker's Signature Spell. The Oathbreaker follows rules identical to those for commanders governing starting the game, the {2} additional cost for each previous cast, and changing zones. The Signature Spell is subject to similar rules, but with two additional restrictions. It can only be cast while its owner's Oathbreaker is on the battlefield, and it always returns to the command zone upon resolution, overriding all other effects and rules, and breaking the functionality of some keywords, such as buyback.

As in Commander, the Oathbreaker's color identity restricts deck construction to cards within that color identity, and no two cards may share a name, with the exception of basic lands. Cards that refer to "your commander" instead refer to "your Oathbreaker".

Unlike Commander, Oathbreaker decks must contain exactly 60 cards (including the Oathbreaker and Signature Spell). Players start at 20 life, and the Oathbreaker format does not include commander damage as a win condition