Submitted by ripvanwormer on Thu, 2006-04-13 20:41
Xag-yi are creatures of pure negative+energy resembling glowing black orbs with tentacles made out of the same black light as their bodies. They are inscrutible, alien things, and it is a matter of debate whether they are truly sentient.
Planescape Monstrous Compendium Appendix III
Manual of the Planes