This is a Tier 2 adventure optimized for 4 level 6 characters. It offers tools to adjust the adventure for larger parties of different levels. Playtime for an experienced group of players should be between 6-8 hours. Expect a longer playtime with less experienced players or very cautious players.
465 years ago a small faction of Kuo-Toa encountered something in the cold abyss far below the surface of the ocean. Fascinated by its power and the way it seemed to grip helpless Kuo-Toa with cold black tentacles they started worshipping it. Gruagloop or 'the Grasping Abyss' became an entity of shadow, gaining strength as it gained followers. The Kuo-Toa worshipped it in small factions out of fear of the darkness. And those mad enough to worship an all-consuming darkness did so in secret. Races from the underdark kept away from it, but some found a strange attraction in the entity and the promise of a world filled with darkness.
120 years later the monstrosity known as Gruagloop was stopped by the Aurora City Watch. They constructed a Vault, a trap, based on the principle of 'Dehheseih' or diffusion. The space between light and shadow, the threshold between the realms. Gruagloop would have to cross the threshold to enter the material plane and the City Watch would trap it as it was doing so.
It has been kept hidden for centuries, until now. The race that originally gave rise to the god has been searching for their mad god and have found it. And another group of fanatics is getting close too. With the Sealing Festival coming soon and with it, the longest night of the year... Interesting times are upon us...