The Crystal Dungeon

Publisher's blurb:

The mountains south of Fort Konuck are full of mysteries. One of them is the mysterious crystal dungeon. No one knows from where and even less when this enigmatic growth of crystals invaded these tunnels under the mountain. One thing is for sure though, crystal expansion appears to be progressing as crystals can now be seen outside, appearing to affect vegetation to the point of killing it.

Originally a simple tomb, what could be the mystery of this crystal growth? No one has entered it for several decades. Information is therefore unreliable about what might still be inside.