So, I need to evolve my lanpent...that was quite a long time ago. I never got the chance to find one because I played when it was just released, and nobody knew where to get one. I still don't know how to get a Dusk Stone.
Please Help Me. Thanks in advance
Non-repeatable - Route 10 (from the Vetern near the northern bridge) - Mistralton Cave (Northeast corner of 3F)
Repeatable - Dust clouds - Black City ($10,000 from Herman)
Dusk Stone (Bulbapedia)
>Route 10, Mistralton Cave, Wellspring Cave (Dustcloud), Chargestone Cave (Dustcloud), Mistralton Cave (Dustcloud), Twist Mountain (Dustcloud), Challenger's Cave (Dustcloud), Victory Road (Dustcloud), Giant Chasm (Dustcloud)
Hope I helped. :) Source