1. In response to the stated question: I also think we're going back to the room with the cistern, given that we don't know what kind of cavern-denizen left a cobwebby message in Leonan's head.
2. Leonan didn't give much of a description of the cavern to Castagyr and Eddicus; instead, he described the presence of some sort of creature "up ahead." Apparently he saw the overall shape of the cavern, but in the (scant?) available light did not see details such as whether there is an open end of a tunnel visible.
3. I do have a copy of the Basic Game, of course, since it is available for free as a .PDF file. I have not looked in it to find the stats of monsters who can place thoughts in the heads of passersby while leaving an impression like a cobweb. First, I think that might be cheating; and second, I think that looking through the bestiary there would certainly be tedious.
4. Just heads up for all: Leonan got a 13 on his WIS check, but both Castagyr and Eddicus got higher than that. It might be possible that Leonan failed a WIS check there, while C. and E. made theirs successfully; or else it might be that Leonan was the only party member in line of sight of the head-thinker, given the fact that Leonan was scouting ahead. I really don't know what to make of that; perhaps we'll find out later if we get much farther.
5. If GameDoc is too busy to keep playing Vottr at the present time, and Axel's last activity on EN World was on Monday, 18 April 2016, do we want to keep the option open of asking mips42 to consider the possibility of seeking to expand the player pool once again?