The underworld boss is a mysterious, hooded figure. He shoots magic at the player and has the ability to teleport.
After making this sprite there were two things missing: Magic effects for his attack, and an anticipation for his attack.
Attack anticipation
So first I added an anticipation move. Before stretching his arms outwards, the hooded figure ducks a little to build up the attack. This will give the player a queue that an attack is on the way.
Magic effects
After adding the anticipation move, I added magic effects to the sprite. Since the underworld contains green demon fire, it makes sense the boss also uses this.