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The Indigo Pass was an enormous dwarven tunnel designed to more efficiently connect Goldrun to Aluar, which were previously only accessible via a long route down the Goldrun River. The tunnel also housed the dwarven city of Kentlock. The Indigo Pass was named for the large marker stones that were enchanted to glow with an indigo halo, lighting the way for travelers.
The Indigo Pass still remains mostly intact, but is infested with kobold warrens and undead from the city of Kentlock.