Oathbreaker is a casual, multiplayer, singleton format. 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 additional 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, breaking the functionality of some abilities, such as buyback.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
