You must have Energy to battle, and each battle decreases your total Energy by 1
If you reach 0 Energy, you must wait until it recharges to at least 1, before you can enter another battle
Demons possess the insidious ability to chip away at one's mental health. Starting at Circle 1, each demon battle that you endure increases your Insanity by 1 point. Every 9 Insanity points increases your Insanity level by 1.