SureAI

I have found the Rhalata temple in the undercity its in the bottom level of the residential barrack Moldwood in the undercity arena you pull a lever and it revels a door that is locked so will you be able to join the Rhalata in forgotten stories as a guild?

I don't know if you can join it, but one of the new quest series should involve the Rhalata. If you want a sneak peek you can use the console command to unlock that door. The temple is well developed but no loot to speak of (except lots of books), and the NPCs pretty much ignore you.