MageHunter |
It's implied it might exist as a homebrew area. I'd personally just make spells available to outsiders that function the same way.
In terms of flavor, mortals have their soul and flesh separated rather than combined like Outsiders.
I would give it a +5 bonus on enchantment spells and the like. See Trap the Soul for reference as well.
Incidentally, Tieflings and Aasimars are Native Outsiders, and so can be bound just like regular ones.