Coal squashed herself through the doorway, angling her horns through first, then her mammoth breasts and then she was stuck. Stuck by something more than the doorframe, because her tiny wasp waist fit through easily, but something had trapped her. She screamed in anger and anguish, tearing at the doorframe with her claws, but while the wood came away easily, underneath there were stones set with glowing runes.
A few minutes later, Professor Finnicus came down the hall, dawdling along merrily with his cane. "Enjoying our 'Succubus Form' potion, are we, Coal?"
"You have trapped me!" Coal raged.
"Yes. Obviously." Professor Finnicus smiled, then cocked his head. "What else did you admix into that potion, if I may ask? The ingredients in the student cupboards shouldn't have been able to manage a Succubus Queen." He eyed Coal's mammoth black-nippled mammaries.
"I don't have to answer you, mortal..." Coal hissed derisively.
"Actually, you do," Professor Finnicus differed. "By the runes and sacred sigils that bind you, and by your name, Coal, I command you to answer me, o demon queen."
"I admixed nothing into the potion," Coal cooed huskily, mammaries heaving.
"Then what else did you do?"
Coal merely seethed, saying nothing, until Professor Finnicus gestured and the runes blazed afire. "I blew a lost god!" Coal admitted, wincing in agony.
"Which one?"
"Wynnnfeld!" she gasped. "Lord of the Centaurs!"
"'Lord' is a bit of an exageration," Professor Finnicus stated. "There's a reason why some gods are lost. But, still, it may be of use to me. I command you, by the power of the seals and your name, to relinquish this power to me, specifically into this prepared vessel." He took a flask from his pocket and unstoppered it, and as he did so, the power drained out of Coal like sand from a broken hourglass. Her breasts sagged and deflated and withered back up, her horns receded, her tail lost its spikes, until all that was left stuck in the ward of the doorframe was a perky succubus.
Professor Finnicus admired the trapped essence in his flask, then stoppered it and put it in his pocket.
"What are you going to do with me?" asked Coal.
"Do with you?" repeated Professor Finnicus. "Well, this is an instructional institution, Coal. I could reverse the potion, of course, but that would hardly teach you a lesson, and besides which, Professor Tratz is having her Applied Demonology class in less than an hour. She usually does a lecture on why turning yourself into a djinn is a silly idea, but this will be equally instructive and will save on magical supplies. In which case, I command you to keep the horns and the little bat wings no matter what form you take, and moreover, I command you to not harm anyone, physically, mentally or socially. And the same holds true for your little imp familiar." Professor Finnicus pointed to Xan, also stuck in the circle.
Professor Finnicus added pedantically, "If you're wondering why your familiar is trapped, the reason is twofold. First, we have the wards set up so that familiars can pass unmolested, even demonic ones. Second, since you are currently a demon, your familiar isn't a familiar anymore, just a lesser imp under your sway, and thus able to be trapped."
"I was going to make the world my own personal hell!" Coal raged.
Professor Finnicus smiled and sighed. "Ah, youth.... I remember when I had dreams myself of being a grand and wicked magician. But not everyone can rule the world, and as marvelous as it is to be a wicked magician, it's far better to be a wicked magician with tenure." He winked at Coal. "And I must thank you for giving me the power of a lost god without having to make any troublesome pacts personally."
Professor Finnicus toodled off down the hall, emminently pleased with himself.