We take a nice long, well-needed rest. I take a closer look at the "rebuke the dead" door, but still cannot determine how to open it. All I can determine is that it is enchanted with Abjuration magic.
The goblin chief eventually comes back and I give him Uttu as colateral, and he doesn't seem to be aware that I can have him return to the Fey at any time to avoid harm, or to return to me. The chief lays out his plans to us, and we concur. The plan is to have the goblins attack the kobolds, and we will maneuver around to attack the cultists in the black robes.
After our next rest, I again cast comprehend languages as a ritual.