How to defeat a demon, he endlessly restores health
have all spells fully levelled, have all cooldown things activated, and have max health at as high as possible.
step 1: transform to Celestian, and use divine retribution once. deal as much damage as possible.
step 2: keep going as Celestian, until Demon General kills you. you will now be back to regular Celica.
step 3: keep attacking until you have around 800-900 health, and transform to Celestian again.
step 4: repeat step 1-3 untill he is dead.