Use 6 booster packs to build your sealed card pool.
Deck must have exactly 25 cards.
Include 3 Domains in your deck and required Battlefields (three Battlefields). If you don't have enough Battlefields, you may use facedown cards as “blank” Battlefields.
Signature Spells only need to be within your Domain identity (they don't have to match your Legend or Champion type).
Chosen Champion / Champion Legend is optional (“you don't have to have one if you don't have one”).
No card quantity limits in Sealed (you can use all copies you opened).
Limited sideboard: Your unused cards from the pool act as your sideboard.