Fog horn, a magical tool that when played surrounds the user with clouds and possibly fog clouds (the monster).

It would be best if some type of non-poison-gas cloud were implemented first; it is probably a bad idea to actually change the terrain around the user into cloud. It would also be good if the obscuring cloud were useful at blocking monsters’ pathing to the player; currently they would ignore it so creating a fog cloud would mostly hinder the player.