Rolth

Rolth, Korvosa's own reprehensable necromancer

Description
A failed Academae student, the gnome formerly known as Rosti is a monster of a person who was expelled after the true nature of his experiments were revealed after his former friend Tosti reported on him. He was using illegally aquired body parts to try to build some sort of golem from their collected parts. The Academae didn’t press charges because it didn’t want to cause a scene—it just quietly expelled him and he’s been trouble ever since. The Guard suspect he’s responsible for nearly a dozen slayings, each involving mutilation to the body, but to date they haven’t been able to find him or locate his lair.

He is a foul man by any definition of the word. Pale and blotchy from scars caused by various diseases he’s exposed himself to (either by accident or design), Rolth wears thick leather robes lined with dozens of pockets that bulge with surgical and mortician tools.

History
You were sent to deal to acquire the body of Gaekhan, the grandson of Thousand Bones, from Rolth's lair in the Dead Warrens. Field Marshall Kroft told you a bit about Rolth.

In the Dead Warrens, Rolth had a number of servants: A small band of derro, apparantly lead by his apprentice, which frequently referred to itself as Vreeg, a particularly ugly ogrekin, Cabbagehead, as well as several of his creations and experiments.

It seemed that Rolth only took the part of Gaekhan’s body he needed to finish his flesh golem’s body—the head—and discarded the remaining remains over the rest of his den.

After raiding his twisted laboratory and killing his apprentice, you didn't hear from him for a while and you hoped that you had destroyed his resources so thouroghly that he wouldn't be back.

He was however merely otherwise occupied overwise. You encountered Rolth for the first time in the Temple of Urgathoa, where he was working on an upgraded version of Blood Veil that raised its victims as zombies. He raved against Tosti (for betraying him in the past), against the party (for ruining his lab in the Dead Warrens) and against everyone in general. He also revealed that he knew Jolistina Susperio and raved at you for killing her.

After a long fight, you managed to overcome Rosti, but he managed to escape, but only after promising revenge.

During the investigation into the cure, Tosti was ambushed by two shadows claiming to be sent by Rosti, who wounded Tosti and freightened the party with their incapability to be hurt, but Tosti and Kyeran managed to kill one and drive the other off.