Web of the Witch World
This Ace paperback, F-263, is the first edition of this title, and was published in 1964. Cover art is by Jack Gaughan.
An interesting tidbit about this book: in a letter to Bill Bowers, co-publisher of a fanzine called Double: Bill, dated October 1, 1963, Andre Norton referred to this sequel to Witch World as "Quest For Kolder," although she did not know when it would be published. She went on to write that she had "glimmerings of an idea for a third book to deal with Tregarth's children who resent their mixed blood and the fact they are living in the twilight of their civilization (which they shall refuse to accept)."