demonic arm

as the fighter finishes the invocation, his arm starts to glow. when the light stops, the fighter's arm has turned fiery, and burnt. 

this spell turns the player's arm into a demons arm, enhancing their strength, and damage tenfold. although this spell would work better for a fighter, it can also get a wizard out of a tough, close-quarters situation, if saved in a scroll, or other enchanted item. the spell enhances unarmed strike by adding a damage increase of 1d20+15(plus strength modifier). if the player is attacking with a weapon, just add +15 to the damage. this spell doesn't dissipate unless the duration is up, the arm is disconnected from the body, or the player wishes for the spell to be gone.