You will find Simone befouling Un'Goro Crater. Do not be fooled by her disguise. Approach her with caution and challenge her to battle.
Klinfran the Crazed:
Klinfran wanders the Burning Steppes. Approach him with caution and force him to show his true form.
Solenor the Slayer:
In the arid landscape of Silithus lurks the fiend, Solenor the Slayer. Undoubtedly disguised, definitely a danger. Approach him and force him to transform.
Artorius the Doombringer:
Artorius brings corruption and doom to all that he touches in Winterspring. Find him, kill him.
Be warned, hunter, these demons must be fought on their own terms. If they feel that they do not outmatch you, they will flee.