Darkstone

Sourced from Blackrock Mountain, a former dwarven homeland in the Earthen Peaks. The city was lost to creatures of shadow. All the attempts to reclaim the city have failed. Only a few returned and all of them had gone completely mad, rambling about "deep evils".

A few shards of the stone were found in the bags of the adventurers and some have been found in the area. Even small amounts have the ability to corrupt an area. The earth turns dark and poisonous, plants wither or turn into vicious animated creatures, and creatures become rabid.