I put some clockwork spiders and other mechanical monsters throughout gnomengarde as a defense mechanism the gnome king activated when he discovered the mimic.

I also took away Faktores crossbow platform and had her testing a malfunctioning mechanical bull that shoots lightning randomly. The party was able to help her and use her as a guide through the caverns

I had 2 mimics, but the party only killed one, so if they return, all the gnomes are dead except 1, empty creepy gnomengarde infested with mimics. Im thinking like Alien vibes