Not much is known about Kazmojen, save for what the party learned from a loose-lipped mimic in Jzadirune.
What the party knows, is that Kazmojen is an Underdark slaver, who employs the rest of the gang in Jzadirune, composed of skulks, dark creepers, and hobgoblins. The skulks and dark creepers raid the surface, take their victims down into Jzadirune, where they are then handed over to some hobgoblins who take the slaves down into a place called the Malachite Fortress. Kazmojen pays the skulks and dark creepers a portion of the proceeds from his sales, and they also get to keep whatever they pilfer from the surface.
The group encountered Kazmojen in the Malachite Fortress, when he was trading the kidnapped children to a durzagon. The battle with Kazmojen was fierce, as his half-troll nature enabled him to regenerate wounds.
The party slew Kazmojen in the Malachite Fortress, ending his slave trade business.