Beliar, the Slave of Sloth or Na'aki-Rihur, is one of the Maeljin.
He is an overpowering spirit, viewing everything in the world as beneath him. Content to wait and grow stronger as entropy swallows more and more of the universe's energy, the Bale Hounds that serve him are also fanatically certain of their own ascension. They attack their enemies with ruthless efficiency, caring little for how quickly a victim dies so long as he does.
Beliar's favored avatar is the Messiah, a bloated spirit resembling an octopus in a pool of tainted Essence and surrounded by a spirit-web. It harvests Essence from nearby loci and freely gives them to local spirits in exchange for their allegiance and service.