Hearing their warforged employer’s collapse, the two shifters slow their advance, look at one another, and shrug. While they wouldn’t shy away from a fight, no one’s going to bother spilling blood without a payoff at the end, and they certainly don’t like the 3:1 odds. They back off (going back to the West) and head north up the tunnel at the T-intersection.

Searching the body of the now non-functional warforged, you don’t find much: a rapier, light crossbow and 10 bolts, thieves tools, cloak, and pack. (None of the gear is masterwork.)

You make your way forward (West) – the only way not blocked by a grate or valves spewing forth sewage. At the T-intersection, you see that North (the same way the shifters went) is also the only way onward, as another grate prevents passage further South.

It is about 30’ up that passageway (where the “C” is on the map) that you find the portal:
A circular metal hatch, set into the tunnel wall and engraved with arcane runes, must be the sealed door that Elaydren told you about. In the middle of the hatch, a glowing circle of mithral depicts the same icon as on Bonal’s journal – the ancient symbol of House Cannith that predates the founding of the Kingdom of Galifar itself, a stylized anvil and hammer.
(OOC: I'm going to assume you want to open the hatch, so tell me how you go about it. )