Domain Expansions are the strongest technique that a Sorcerer or Cursed Spirit is able to use in a battle in Jujutsu Kaisen: Cursed Clash. It's an incredibly powerful technique that essentially creates a barrier around the opponent, which has been infused with the user's Cursed Technique, making them more or less a sitting duck as they are at the mercy of the person using it, who is able to control the space in any way they would like.