Dreamweaver — C.S. Friedman

The final book in the action-filled urban fantasy Dreamwalker trilogy follows Jessica Drake as she navigates the dangerous landscape of distant worlds and dimensions

When Jessica Drake learned that her DNA didn't match that of her parents, she had no idea that investigating her true heritage would put her family's lives in danger, and ultimately force her to cross into another world.

There, in an alternate Earth dominated by individuals with frightening mental powers called Gifts, Jessica learned of a curse within her blood, one so terrifying that all who possessed it were destroyed on sight. For she is a Dreamwalker, and the same dark Gift that allows her to enter the dreams of others will eventually destroy her mind and spread insanity to all around her.

Now the deadly wraiths known as reapers, created to hunt down the last Dreamwalkers, are starting to target her family. In order to destroy them she must seek out a mysterious shapeshifting tower where the secret of the reapers' creation -- and her own Dreamwalker heritage -- can be found. Joining forces once more with the ex-Shadow Isaac and loremaster Sebastian, she travels to the Badlands, a region on the alternate Earth from which no traveler has ever returned.

But her efforts to unlock the secrets of the past will soon ignite the flames of an ancient war, as the dead -- and the undead gather to fight their final battle against the Dreamwalkers -- with Jessica and Isaac on the front lines, and the fate of her entire homeworld at stake.