Stormqueen!

Blurb

Stormqueen! is a science-fiction novel by Marion Zimmer Bradley in the Darkover series. Originally published in 1978. It was republished in 2002 as part of the Ages of Chaos omnibus.
Stormqueen! occurs two hundred years prior to Two To Conquer, in the period of Darkover's history known as the Ages of Chaos. The underlying theme of Stormqueen! is a breeding program, undertaken over centuries, to produce stronger laran gifts, resulting in individuals like Dorilys and Allart, whose gifts are potentially lethal.
Though it is mentioned as an aside, this book contains the moment in the Darkovan timeline when the Ridenow of the Dry Towns overtake the Serrais domain, merging into Ridenow of Serrais.