At korthos there is that lvl 1 quest called Stopping the Sahuagin. You help Gunnar Bauerson to stop the Sahuagin plans to awake an ancient Devourer beast sealed by giants.

The prompt of this quest always made me curious. What beast is that? Is it the undead creature called Devourer? Or its a Devourer's minion , deity followed by the Sahuagin in this arc?

I always been curious about this underground complex and what expects us behind those locked bars. It gotta be a powerful monster to have such a complex system just to hold it instead of being overpowered/destroyed by giants theirselves.
Is it mentioned anytime after this in any part of the game? I always imagined returning to korthos and fighting this monster as a raid boss, if its the Devourer creature it would fit well as an Raid Boss.

What your thoughts on it? Any lore master out there that could shed a light on the matter?