well, since the crystal is in a giant cave, there could be a large amount of ambient (non-directional) light, reflected by the roof and walls near the crystal. This would eliminate much of the shadow, making things fairly \"normal\" on the first two levels
Still, there will probably be many areas in planeshift that are in permadark. Fungus, mold, and bare ground will rule here.. or perhaps there will be thermally active areas and some sort of vegetation living off that as well.