changed the cover and the wording the spellcasting table

After usig this system for my new game, "The mage and the knight", i liked the way i described things better in the other manual, so i decided to reword things a little. 

changed the way the consequences are described in the spellcasting table while still leaving them open to interpretation and not too specific. 

also, i forgot to update the cover art in the file with the new one i used for the shop page uhuh.