In the Spiny Mole's tunnel in Nova there is a small "X" on the wall when you first enter the tunnel. When you first visit, this has no significance. However, when you return to the "X" after visiting Shadra the "X" will now be a hole that leads to Glissina Cave. In Glissina Cave, you must fight your way through many battles to the final floor. Once there you get an item that helps you defeat Master Macadameus. Note: You cannot enter Glissina Cave if you have already defeated Shadra's first form.