There are two caverns northwest of Cyseal that can be entered through trapdoors. The first is at the location of an aggressive zombie dog and the second is under the Pyromancer and Fire Elementals.
- Clear the entrance to both Caverns.
- Split one member of your party from the group. Send him/her into the Zombie Dog Cavern.
- Send the rest into the Fire Elemental Cavern.
- Read the tablet at the Fire Elemental Cavern and use that sequence to press the buttons in the Zombie Dog Cavern.
- (Optional) Use the Teleporter Pyramids or just run your fourth member to the other cavern for a better advantage.
- Kill the Mysterious Opponent and loot the amulet. Enter the trapdoor that has just revealed itself and use the amulet on the pedestal.
- Perform the same steps for the Zombie Dog Cavern. I.E. send one to FE Cavern and the rest to ZD Cavern. Read the tablet at the ZD Cavern to press the buttons in the FE Cavern.
- Fight and loot the enemy and enter the trapdoor.
- Use the amulet on the pedestal to take down the force fields.
- No XP for killing each Mysterious Opponent, but decent potions and miscellaneous loot.
- 4 Chests with good loot.
- The Mirror Inside achievement (for Steam game).