Hi!
I'm the overlord of a group currently on silver level. Last Night we stopped right after they opened the blue door into the last area of this Rumor.
There arose a question of wether the monsters could simply open the door and kill the cub themselves.
This makes it pretty impossible for the party to rescue the cub, but on the other hand if the party simply kills of all the monsters and THEN opens the door (assuming the monsters are unable to open the door); then it is very hard to neigh impossible for the overlord to kill the cub. This would only be done by initiating another spawn, unless the heroes are covering all the areas, or for the overlord to play a Dark Charm.
Comments, rules or how you play are all welcome.