Sunwarped Peaks

From publisher blurb:

Try to Find Some Shade

Sunwarped Peaks places a group of adventures in the path of a dangerous warlock who does the bidding of a deadly Patron known as the Prime Star. Duergan, the warlock in question, has begun a complex ritual in the mountains bordering the small village of Jartan's Shade. Massive mirrors and lenses twist light into unnatural portals that have created a gateway for lesser sun elementals to enter our world. Duergan will not rest until the portals are large enough to allow the Prime Star to enter our world and all land becomes sun scorched.