Knights in the Nightmare(2008)

Somewhere between heaven and the underworld--in the center of a quiet lake--stood an ancient castle known as Aventheim. One night, without warning, denizens of the netherworld emerged and slaughtered the kingdom; nary a soul was left alive. Within an abandoned, long-forgotten church deep in the woods, a wisp is set free. Bereft of memory, it is drawn toward a monster-infested castle and re-awakens the souls of vanquished knights, leading them back towards the fallen stronghold to confront the very forces of evil that took their lives.