The Legend of the Holy Grail is a mod for Spear of Destiny, made by Wolfrost. It was released on March 8, 2014.
The mod features 6 new levels and a handful of coding changes, including in-game messages. Sprites come from various places, including Spear Resurrection and WSJ's Heer Pack sprites.
6 levels are featured, with the final level's elevator leading to a blank level that cannot be completed. A full version was never released.