The Pluto Door

1. It avoids light.
2. It runs into the crevice to avoid light.
3. You have to put some light source in the crevice to drive it out.
4. The only light source that fits is the splinter.
5. Now it runs away from the crevice because there's still some light from the splinter.
6. You need to turn on the lantern to track it down.
7. It runs away from the lit lantern, but never runs into the bomb room.
8. If you leave the lantern in the middle underground room while lit, the skink will go the room with the crevice. It's a creature of habit.