Banishment - Domain Expansion

One creature that you can see within range must succeed on a saving throw according to the user's spellcasting ability or be transported to a demiplane, or a "domain", either on another plane or overwriting the given setting (work with DM), for one hour. While there, the target has the charmed or paralyzed condition if good or neutral, or the frightened condition if evil (can work with DM to decide on others as well), and cannot leave the "domain" for the duration. When the spell ends, the target reappears in the space it left or in the nearest unoccupied space if that space is occupied, with the lingering psychological effects of having experienced such a fate.

If not otherwise occupied in combat, the caster of this banishment may follow that creature into the domain on their next action. This does not require use a spell slot to accomplish.

The domain appears as a hemisphere with a 60 ft radius/120 ft in diameter. The banished creature cannot leave until the duration is up, but the caster may if they so choose. You cannot see inside the domain from outside. The domain represents the character of its caster, and as such gives its caster advantage on initiative and spell attacks when inside the domain. 

If the target is an Aberration, a Celestial, an Elemental, a Fey, or a Fiend, the domain instead has an appearance in opposition with its creature type (for example, a fiend would be banished to a celestial-appearing domain) The caster still has the aforementioned advantages.

Using a Higher-Level Spell Slot. You can target one additional creature for each spell slot level above 4, and if a player succeeds a charisma saving throw, be brought with you equal to the domain. This can be only be used equal to the amount of creatures targeted (Ex: when cast at level 5, can banish two creatures, and bring one player character into the domain with you on your next action).

-> Suggestions welcome. I created this to possibly use in a pretty relaxed campaign I'm in and isn't meant to be too much more than a personalized boxing ring with some flavor.