Filmen du letar efter är Krull .
Prince Colwyn is found and nursed by Ynyr, the Old One. Ynyr tells him the Beast can be defeated with the "Glaive", an ancient, magical, five-pointed throwing weapon. Colwyn retrieves the Glaive from a high mountain cave before setting out to track down the Black Fortress, which teleports to a new location every day at sunrise. As they travel, Colwyn and Ynyr are joined by magician Ergo "the Magnificent" and a band of nine thieves, fighters, bandits and brawlers. Colwyn offers to clear their criminal records, successfully enlisting Torquil, Kegan, Rhun, Oswyn, Bardolph, Menno, Darro, Nennog, and Quain. The cyclops Rell later joins the group.
....
The Fire Mares, steeds that travel so fast they leave a trail of flame and can effectively fly, are played by Clydesdale horses.