Domain Expansion

Domain Expansion is an advanced Barrier Technique that manifests the user's Innate Domain and traps their target inside it using a barrier wall to create a separate space. Once inside, the user's cursed techniques are improved and cannot be avoided.

Description
Domain Expansion is the most supreme ability of any jujutsu user. By using a barrier technique to create a separate space, the user can realize their innate domain with cursed energy and trap their target within it. The domain is embedded with the user's innate technique to complete the formation.

Once inside, the user's jujutsu is greatly amplified and any attack deployed is a guaranteed hit. Using a hand sign or another sort of signal unique to the technique is one of the requirements to activate it.

Manifesting an innate domain with cursed energy requires a lot of power, and erecting a barrier requires even more so. Domain Expansion is a difficult technique to learn that most high-level sorcerers are never able to master. Among cursed spirits, only special grades like Mahito, Dagon, and Jogo have shown the ability to use domain expansion.

Drawbacks
Domain Expansion requires an immense amount of cursed energy and the user's innate technique will become unstable for a brief time after deactivating their domain. Additionally, the user's cursed energy reserves will be extremely low and it is unlikely they'll be able to cast a second domain. Satoru Gojo is the only person capable of using domain expansion more than once a day.

Even after achieving the activation of domain expansion with a cursed technique, a domain can still be incomplete if the user is unable to fully form the barrier. The technique won't provide the guaranteed hit, but unlike improper innate domains, the user's cursed techniques are still vastly improved.

Countermeasures
The automatic hit provided by a Domain Expansion can be countered with a blast of cursed energy, but this method is impractical for most. The only true way to counter Domain Expansion is for the target to expand their own domain. This automatically nullifies the automatic hit, and both Domain users will enter a struggle where the more refined domain will win.

Escaping a domain surrounded by a barrier is almost impossible. However, the more the barrier is reinforced from the inside, the more vulnerable it is to penetration from the outside. In specific situations, an ally of the domain's target can break in to rescue them.

Domain Expansion struggles don't always have to result in one domain conquering the other. Using Domain Expansion against a more refined domain can create a hole in the barrier for them to escape from as well.