What is sugoll?

Some articles on sugoll:

Saga Of Pliocene Exile - Pliocene Races - Tanu and Firvulag - The Howlers
... only, and they have their own king, Sugoll ... Both by Sugoll's own assertion and the attestation of the rest of the Howlers, Sugoll is first among the Howlers in all things - mental power, physical ability, and, most of all, physical deformity ... Sugoll, although often robed in an illusory body, is the most hideous and frightening of all the Howlers ...