Rezmir had been sent here to retrieve a piece of a mechanism to open up a set of dwarven ruins that had served as a focus point for the funnel.
Rezmir is part of a small clan of dopplegangers that servers an abolith by the name of Pha-zoth. This being is from the far realm (a place beyond this reality), and it’s motives are… hazy, though it is said to “Speak the will of Olyhydra”. But it seems to wants access to places of old magic, places used to forge great weapons. It first sought to gain control of the forge at Wave Echo Cave, but having been thwarted set it’s sites on larger prey… the forges of Gauntlgrym. It seems it wishes to flood the city in order to facilitate its travel to the city. And to do this, it seeks to co-opt the old “funnel” that feeds water elementals into the forge.
Of the doppelganger clan, 3 remain free. One has been sent to Luskan to gain a place of leadership in Ship Kurth, in order to watch over the Arcane Brotherhood as it rebuilds. The second was sent to Mithril Hall to find information on Gauntlgrym. The last has traveled to Waterdeep in the guise of a merchant, though it’s specific goals are unknown to Rezmir.
The party was tracked, first using the coin then using the sword Grace claimed from the previous doppelganger. Pha-zoth opened the portal here, and Rezmir was to use the puzzle cube to return to a staging area in the Spine of the World and to await further orders. The lodge there is guarded by a person called Talis, along with a few body guards.
The Watery Eye is a key to Pha-zoths realm.