There are whispers of a Dark Magic Guild around the castle, but only in furtive and hushed tones. No one wants to admit that some wizards use their knowledge for nefarious matters. You didn't hear it from me, but some say the Dark Magic Guild is even secretly housed within the Magic Guild itself. You just have to know where to go and the secret to getting in. Maybe Horny the Toad could help you find it. It's rumored that he has some dealing with this dark sect.
The Magic Guild was founded by frogs seeking truth, order and understanding of a cruel and chaotic world, so it is ironic that some frogs have used that knowledge for personal benefit and gain, but such are the capricious ways of frogs. The question is: if you go down that hole, can you get back out again? This journey is only the most adventurous and those with nerves of steel. It is not for the faint of heart, but you have to ask yourself, 'Can you look a demon in the eye as its fangs drip with blood and saliva and ask it to do your bidding?' If you can, maybe it will bring you riches. Maybe you will meet some like-minded companions...but are you willing to risk it all to find out?
It is rumored that the Dark Magic Guild is the inverse to the light of the Magic Guild. Even the world in which it resides is like the mirror image of the world of light. It too, has levels of experience for practitioners of the dark arts.