Valnor is a high level demon known for granting warlock and necromantic powers in exchange for souls.
Valnor is the source of Jadzia's powers as well as many others. After stumbling on an artifact that allowed her to collect souls from those she killed, she came up with a plan to reclaim her own. She (some would say foolishly) traded several souls, including that of Darmock) in trade for her own soul.
Shortly after, it might appear that Darmock, now in Theria's version of Hell, killed Valnor and claimed his position for himself.
A decaying corpse complete with bugs moving through his flesh.