Klątwa Zarsthora (Zarsthor's Bane)
This is a Polish edition of Zarsthor's Bane, published by Amber in 1991. The cover is from a painting from the 1970s by Boris Vallejo entitled "The Couch of Silistra" and originally used on the book Couch of Silistra by Janet E. Morris, published by Bantam in May 1977.