"Major Heal" spell:
This is the most powerful of the regular heal spells, only bested by Revitalize. Major Heal is better than Revitalize in the sense that casting it does not remove all the spells the target player is affected by. In other words, if the target is affected by the Sanctuary spell, casting Major Heal does not remove the sanctuary, Revitalize does.
Major Heal Tome:
To acquire the Major Heal tome one must best some difficult creatures, it is not wise to try and acquire the tome alone. The Major Heal tome is found under the Great Forest of Mist. Quest through the Mist until you are "Outside a Misty Cavern." Go to the depths of the Caverns until you find a Crumbling Passageway. You must find open a series of doors, fight a series of creatures acquiring Rusty Keys. Continue your journey, mostly south, fighting, killing, and finding Rusty keys. Eventually, if you're able to see those which are hidden, you will find a Ghost of Joseph. Ask Joseph things about the Demon until he gets upset and attacks. Use his key to unlock the final door south. Enter that last door with caution, the Greater Demon is not to be taken lightly. He is rumored to scream for help from his lesser demons. After besting the Demon you are able to unlock his Altar and remove the tome for Major Heal. The small pearl necklace found in the altar can be traded in Elondale for a coveted item for fighters as well.