When I reached the end of the Dwarven vault, I used the Unstable spellbook that I got after the boss (in hopes of getting a scroll of mapping effect), but i didn't have enough charges to get a choice of what scroll to use, so it used a scroll of return, which brought me out of the vault and into a homebase raid which I was unable to fight, since they were enemies of the level I was fighting before I went into the vault.