Demonic Repulsion [30 pp]
You create an invisible forcefield that prevents entry to and provides nigh-impregnable protection from demons. No demon can cross it in any form or dimension and most effects or attacks they employ are stopped cold. The field does not protect from perception attacks (you can still see and be affected by them through it) or a clever demon attacking indirectly (i.e. stones thrown by demons are not demons themselves)
Create 10 (Subtle 2, Sustained, Affects Insubstantial 2, Dimensional 3, limited: only vs demons), Immunity 10 (Demonic Descriptor, sustained, affects only others, linked to the Create effect)
This is the ultimate protection from demons for a reasonable price. Basically an invisible barrier that is only solid against demons. It prevents them from entering because it's solid (even against incorporeal or teleporting demons) and a creature can't move inside a solid object and it is also invulnerable to demon attacks so demons can't blow it up or claw it to bits. A demon can still use effects that don't require line-of-effect through the barrier, or employ ranged attacks that aren't demonic -throwing stones, directing nondemonic minions against you or shooting at you with a machinegun- so the protection is not absolute.
Of course, no protection is absolute.