You'll get this in level 6 when you find the Mythical Book and read it. Somewhere in the level there are some stairs leading to the Chamber Of Bone, you may have already seen it but couldn't go there because it's in an enclosed area. Well, now is open for you to go in and get killed. The monster you'll fight here are Illusion Weavers, Skeletons, and Horned Demons. You can get a lot of good stuff in this level if you know where to look. First go to the right and trhough a hallway where you'll see a burning upside-down cross, keep going, pull the lever and a door will open that will give access to a room with a chest and some goodies inside. Now go to the other side and will be a hallway just exactly as the one you were, pull the lever and return to the other side. Just in front of the burning cross, a door opened revealing another room with a chest. gather up the stuff and prepare to enter the chamber. Be sure to have the Firewall spell. Go enter the room in the middle, you'll know which one 'cause its the one filled with bones. As soon as you open the door, shoot two Firewall spells, the room is shock full of skeletons and this is the easiest way of killing them. After you kill the skeletons, keep going to a large room with a couple of Horned Demons and Illusion Weavers. Kill them and read the book that's there and you'll learn the Guardian spell. That's your reward. Enjoy.