Mouse Scout Armada
We came down out of the hole rested and raring to go. We spent some time trying to figure out how to advance, but we were presented with a number of doors, and no clear path forward that didn't leave us isolated and cut-off. I had some vague concerns there were bad guys behind us, but the others counted and said things looked ok.
I was casting about for something to do when I recalled my ring. With it, and a bit of a goodberry, I was able to coax a small furry friend from the wall. After a bit of bribing, I managed to convince both of them to scout the way for us. We got a decent, if mouse-centric, view of the terrain before us. We knew the thieves withdrew towards the rooms that led to the upper floors. We also knew that there were secret doors the thieves would use. The mice knew this, and promised to inform me when they were spotted.
With that in mind, we pushed forward, eliminating a pocket of resistance through the use of trickery and illusion. After that, we found the Big Bad, standing in a room. We know there are at least 1, possibly 2 (or more) casters in their midst. Steeling ourselves, we look set to charge.