Andre Norton's dream sagas; two novels collected together for the first time in one volume:

Perilous Dreams
Tamisen the Dreamer, is trained to walk through her dreams to other places, other worlds. But when she is asked by the crippled star traveler Lord Starrex to take him into a dream world where he can regain his legs and his life something goes terribly wrong. Someone, or something, stalks this world, and it does not mean well to Starrex or to Tamisen.

Knave of Dreams
For Ramsay Kimble, sleep means nightmares, and he avoids it whenever possible. But now a car accident has catapaulted him into the very world he most dreads: the horror world of his own dreams. But here he is not his ordinary self, but a nobleman from a fair country, possessed of power to fight back, defeat his nightmare visions, change his dream world—and ultimately rescue his life from the terror that stalks him.