Beast Forge Cavern is one of the caverns found in The 99 Caverns. It was named after the Western Mech Forge, more commonly known as the Beast Forge, the source of almost all Mecha-Beast in the 99 Caverns but was destroyed by Dr. Blakk using his Gattler.
Mecha Mutiny is an episode where the Shane Gang is out hunting a very speedy slug (Hoverbug Slug). During the chase their Mechas malfunction. Back at the hideout Kord tries to figure out what the issue is but he can't. He thinks it might have something to do with the new upgrades he got from his friends back at the forge (a factory of Mecha Beasts) so they head there to have it checked out. When they get there they find that the cave trolls that run the place have been captured and replaced by Blakk's men who are attempting to corrupt the cores of the Mechas by using Dark Water.
Eli tries a Fusion Shot on Dr. Blakk's unstoppable train but he uses the wrong slugs (Burpy and Beeker) and shorts out his gang's slugs so they cannot fight). The Forge has been destroyed by Blakk's Gattler. The Shadow Clan confront Eli and teach him how Mo has the ability to allow the Slugslinger to see a slugs aura. Eli, learning more about the double barrel-fusion shot, confronts Blakk's Gattler and destroys his new Slugterrian Express train with Torch and Buzzsaw.
- It is also called the Beast Forge and its inhabitants are Cave Trolls.