30 Warriors -- Freemen and Captives -- to populate your arenas.
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.
A cave with weapons sunken into the walls, blades sticking out of the floor and ceiling, and so on. Possibly, any weapon used in it could be torn out of the hand and sink into the stone.