Glissina Cave secret - In the Spiny Mole's tunnel in Nova, there is a small "X" on the map when you first enter the tunnel. On the first visit, this has no significance. However, if you return to the "X" after visiting Shadra for the first time, the "X" will turn into 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: Be careful as the monsters in Glissina Cave can be tougher than the final Boss. Also, you cannot enter Glissina Cave if you have already defeated Shadra's first form.