[@Archmage MC]The cultists that Mamoru and Gromgard met while chasing after the goblin artists. They killled most of them, and Gromgard's goblins - and Mamoru - captured less than a handful, three in total I believe. They were then sent to Gromgard's dungeon, for interrogation. Mamoru learned that they belonged to a cult that targeted travellers and homeless people, who they then sacrificed at crude ritual sites to their god.

That's about it. For deeper details, I suggest [i][b]re-reading[/b][/i] the relevant posts of Lu and Rock respectively.