no, its a special abilty, like flying. Just assign it to an empty NumPadKey. Look at the readme. BTW 'Taunt Fly' works for both CalamityAngel and Abyss.
Although it drains 50 life, if you consume anyone nearby, you'll get at least 50life back, and if theres more than 1 person, you just got free life, 2 or more kills, at least a double kill and saved ammo. And possibly they're weapons.
Nightmare is a very good class to be...