30 cult members, of varying levels of sanity and skill. Divided into Guilds for convenience and clarity. Could potentially be used as 30 gang members, depending on your needs.
It is a good sized temple with all the appropriate attendents. Who is in the temple running it?
All spell casters gain their abilities through a form of demon possession. So in order to gain magical abilites, PCs must track down and trap demons. Of course there are some pretty powerful demons, if the demon is stronger than the PC, the PC could find themselves subjugated to the Demon's will.