you have the sense of being elsewhere. For a moment, you feel suspended, just on the threshold, but then your back in the decayed dungeon as before. If you head to that door, as indicated by Forge, then you bypass the (faux?) natural cave, go through the hall that may have been divided, and head into the smashed up tomb place. (these are all described a few posts up, and are just as you left them).
The others follow, and feel and see the same.
Lucian exits into a clearing, going through the double doors not actually exited before. (or at least pokes his head out). He feels himself return to the fey Aether. Several corpses, which have almost decayed to skeletons and are clad in various pieces of broken armor, lie scattered about. Beyond, you see more walls, made of the cairn stones. These may be building walls. And they may, may enclose places that don't match the halfling's maps. You see no doors or windows in these walls across the clearing.
But you are probably looking at the corpses.