Spectres of the Last War
Aberrant dragonmarks are a stigma to all in Khorvaire. They only have destructive powers, related to disease, madness, and fear. Many abberant marked people were destroyed almost 2,500 years ago when the nascent Dragonmarked Houses started the War of the Mark. Interbreeding between the houses stopped and those with powerful aberrant marks, such as Halas Tarkanan and the Lady of the Plague made their last stand in Sharn, destroying the city in the process.