I was curious how the Companion App would handle this... (v.5.1) at the beginning it specifically tells you to defeat all monsters on each level before returning to the stairwell and making your way up to the next level.
Trying to step back onto the stairs prompts the message "Monsters prevent you from leaving the area. You must defeat them before moving on."
I see that (rightly or wrongly) the App doesn't prohibit ANY actions while standing on the staircase (spells, artifacts; even searching as long as no monsters are present).
In fact, the App handles things very differently. Zargon does NOTHING until either someone searches for traps OR a hero moves adjacent to one of the bookcases (which triggers the illusion to dissipate). If you search for treasure, trigger a wandering monster and kill it, then try to move all heroes onto the stairway to leave, the prompt that you have to defeat all the monsters appears again, prompting the heroes to keep trying things until they've triggered the illusion.
In the App if you kill all the formerly hidden monsters, but before leaving, trigger a wandering monster with a treasure search, any wandering monsters must also be defeated before the heroes are allowed to leave.






















