While researching something else entirely, I glanced at the passage on the mirror of life trapping purely by happenstance.
Because of the fluid nature of this mirror’s possible past, it may contain up to 12 random creatures already.
How they got there and why they ended up near the mirror could be any number of reasons.
That means this encounter, if you set it up right, could be infinitely adjustable to your group’s level and abilities. It could be a campaign starter. It could be a campaign ender — even if only by accident.
Since the contents set the challenge level, take care in making sure you stock the mirror wisely. For the purposes of this encounter, only one of the 12 cells is free, so as to not trap the entire party, and to deliver enough random oddities to truly challenge your group.
This encounter should only trap one character, leaving the rest to solve the problem. It may well set up one of those moments where the entire party says, “What have we done?”
It could also be used for a session where one of the players couldn’t make it, and narratively their character winds up trapped in the mirror.
Encounter Type: Puzzle and combat
Map: Isometric cavern room
Lighting: N/A
System: 5E
Length: One shot
Installation Type: Addon
License: Roll20 End User License Agreement
(Personal Use Only, Do Not Distribute)