Neat idea! I found the big monsters to be useless at the begginig of the game - you can't place them unless the team is already buffed, but they take up space in the hand intead of the usefull cards. So one thing that would be nice to see is the ability to place monsters and bonuses in the room beyond the next one. So you can drop a taurus near the end and just hope that the characters are strong enough by this point. You can pair it with the ability to choose player path (although I understand, that it kinda goes against the idea of DnD session) or placing some preexisting monsters on the map.
Overall the game has a lot of potenntial. Good job!