Just do some sketches for 4 new heroes: the nurse, the reporter, the “mime” and the miner.
The “mime” is the most exotic character: He will be able to push invisible blocks in dungeon and fake death for monsters.
The journalist will be able to take a picture of the day, a sort of super save. He will also flash monsters with his camera to avoid danger.
The nurse and the miner are more classical characters. The first can heal other characters, the miner can use dynamite and break walls.
I have other characters in mind but i am not sure i will have time to add them into the game.