Hey hey, thanks for reading. The way you describe the mountain is basically how I perceive it. The Rinkrank entry bit is from the fairy tale and so his asking to be let in a trigger for PCs who know it to realize that can trap his beard in a glass window or door. It is definitely a fairytale conceit, telegraphed by his song. The glass post is mostly meant to act as a last place the beast will go without a push, but the writing is from the fairy tale: the Princess on the Glass Hill (or the Maiden on the Glass Mountain) where the youngest son of three uses magic horse to climb the mountain and win her hand. The author is ostensibly a king, taken from his daughters by the fog (leaving them orphaned to the village). Glad you enjoyed it, having run it I can say that it definitely is a bit cryptic in that the PCs without knowledge of the folklore will find somethings to inscrutable but I think that actually added quite a bit to the fairytale nature of the game and the players all really seemed to enjoy the strangeness of it.