Getting to the magic worlds is probably the bigger problem for the demon, it’s the creating the body on that plane that’s hard to do. That’s why you spawn half demon babies to go around collecting mana to help you come into the world.
Getting back short of dying is also very hard. In a really low mana world you either need to use Astral Travel (and so need another plane), Die (lose the expensive body) and return to the Abyss, or have someone with a lot of mana create a gateway from outside for bodily travel.
Telepathy is a form of animagic every where you go…the mentalists do it in Astlan (and Mind Reavers) so what you find in other worlds is pretty similar to that…it doesn’t generally have a high energy requirement so it’s great when levels are lower.
“Mutants” with a gift for ESP/Seeing/Scrying/Telepathy/Empathy etc are pretty common. These are people with a real gift for animagic….