Medusa

Medusa is a demon found in Iris and the Giant.

"If I touch the gorgon I will be petrified. She can also resurrect her friends."

Location
Medusa can be found on Floor 10C in Path of the Giant and Floor 11C in Path of the Ferryman.

Path of the Giant

 * 1) Take the secret route on Floor 9

Path of the Ferryman

 * 1) Take the secret route on Floor 10

Strategy
You will appear into a room filled with petrified demons, Medusa will be out of the battle area.

Not only will Medusa deal damage, but on each turn it will unpetrify a random demon in the room. Before bringing Medusa into the fight you can destroy the petrified demons by clicking them (no cards required), you should do this to bring demons that you are more equipped to handle to the front (e.g. if you have a Feline Bow in hand then bring Cat Archers in range). Do not have Mice in the battle area, they will allow Medusa to attack twice and unpetrify more demons.

Once you are satisfied with the demons you will be facing, bring Medusa to the front and focus solely on it. Medusa will have 2 armor. Take it out quickly and you won't have to fight many demons.