Blood Reign: Curse of the Yoma (1989)

To avenge the woman and friends he loved, one lone warrior must seek out and slay his former comrade... but how do you kill someone who is already dead? The solitary ninja must find the answer to that very question, and the ancient secrets of the world's oldest clan of professional assassins are pitted against the forces of evil! From nightmarish battles in which blood-soaked clay literally becomes the feeding ground for the dark creatures that lay in wait beneath the surface of the earth, to flesh-eating stallions and shape-changing spiders.