And the Exile Seal to the Spiritual Realm they created can directly banish monsters to the Spiritual Realm.
If this monster doesn't have the ability to cross the boundary, it will be permanently stranded in the Spiritual Realm.
Although it's likely to be dissolved and assimilated by the Spiritual Realm, transforming into a Spiritual Realm monster, at least the crisis is averted at that moment.
Even if it has the ability to cross back from the Spiritual Realm to the Material World, it cannot return immediately. Crossing the boundary takes time and will trigger significant vibrations, giving the disadvantaged warriors enough time to regroup or retreat comfortably.
The key point is that once the monster is exiled to the Spiritual Realm, it becomes exposed to the firepower range of the dreamscape.
As long as Rod marks the monster, regardless of where it's exiled to in the Spiritual Realm, the Spirit Realm Strike can attack it.
