1

 Whole Truth: Duladarin star elf druids created a massive dungeon beneath the Luna Valley to lock away a terrible evil.

2

 Partial Truth: Duladarin star elf druids created a massive dungeon beneath the Luna Valley. The purpose of this dungeon is unknown.

3

Truth and Lie Mixed: Duladarin star elf druids created a massive dungeon beneath the Luna Valley to lock away a massive hoard of treasure. They intend to come back for it someday.

4

Lie: Duladarin star elf druids created a massive dungeon in the sky over the Luna Valley to escape the fate the rest of their people suffered, whatever it may be. They are still living in a floating cloud fortress somewhere.