Banishing Enchantment + Ghost Mob

I was thinking about having an enchantment like Bane of Arthropods and Smite, but adding a new undead mob type that takes little to no damage without the Banishing (I-V) enchantment. These new mobs could be in a mid to late-game area and appear less often otherwise to balance difficulty, which would make it a challenge and a necessity to obtain Banishing. Especially if there's dungeons with loot guarded by these ghost mobs.

Coversely, Banishing could deal extra on mobs not from the current dimension you're in