Barbarians and Black Magicians(1977)
(The fourth book in the Flashing Swords series)
An anthology of stories edited by Lin Carter
The Bagful of Dreams - Cudgel the Clever by Jack Vance; The Tupilak - The Merfolk by Poul Anderson; Storm in a Bottle - Brak the Barbarian by John Jakes; Swords Against the Marluk - Deryni by Katherine Kurtz; and The Lands Beyond the World - Elric of Melnibone by Michael Moorcock.
Used availability for Lin Carter's Barbarians and Black Magicians
October 1977 : USA Mass Market Paperback