"Minotaur, yes. You there shall become the first minotaur."
The voice is coming from directly behind you, you turn around and see a hooded figure. His black cloak hides his features, but you can make out that he is densely muscled. He reaches forward and touches your head, as his hand presses into your temple, you begin to feel strange. The wizards keeps one hand on your temple, then moves his other to your cock. He presses it, then begins rubbing your shaft. You grunt as your brought to full erection, then cum. Your seed coating the wizards sleeve.
After you cum you begin to feel... empty. You need something, something in your balls, something... on your cock. The wizard moves his hand from your head, stepping back and taking off his hood. You can see now that the wizard himself is a minotaur, his bull face in a twisted grin as he watches his work.
Suddenly, you retch forward and grab your chest. pain pushes through you as you begin to gain muscle. Your lack of abs turns into a 6-pack, then an 8-pack. Muscle is stacked with more muscle, the painful expansion moving towards your now enlarged arms. You start to examine your arms, you press the new muscle with one hand, feeling your new firm form.
You take this moment to look at the victims, something in your mind telling you that they're soon to join you. They all look at you intently, most scared of your transformation. You can't understand why they look so scared, you're becoming something great, something you need to share. Your thoughts are interrupted as you fall forward, the muscle reaching your legs as they press forward into hooves. Your fall is interrupted as the wizard grabs you, he supports you as your hooves shape, you thank the wizard for his kindness by embracing him in a kiss.
With your lips locked, you start to feel your face press out. Your mouth becoming longer and your nose becoming wet. You reach your hand down to the wizards cock and begin to stroke it, he thrusts idly as you feel pressure from your head. Your horns have started to grow, the wizard moves his arms to them in examination.
Finally, pressure builds in your ass as you feel a tail start to emerge, fur spreading from around your tail and moving to your figure. Your legs are covered in fur, then your chest and arms, then finally your head. You break the kiss as you roar, your balls filling with new seed, and your mind filling with thoughts of new victims. So many victims are here, so many people to stick your cock into and pump full of your seed. You smile as you start to feel faint, your consciousness leaving you as you rest on the wizard's shoulder and sleep.
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You wake later in an unfamiliar location, you look and see stone walls and a stone roof. You shake your head as you stand, your bull body filled with strength and... need. You look down at your proud bull member, the shaft long and thick, the balls huge. It rises to attention, and you moan as you feel it sway with your movements. You are full with seed, you need release. You begin to masturbate, stroking yourself as quickly as possible. But no matter what you do, you are unable to cum. You roar in anger, then hear the sound of the wizard.
"My lovely beast, do not worry. I need you full of strong seed to spread, to make our tribe with these victims. Yes, our tribe, when you are done I will take you as my partner."
You grin and nod, imaging the pleasure that you will experience as the wizard enters your ass.
"For now, do as I request. You and all the bulls you make will only be able to cum inside humans. Once the final human is made into a beast, you will be free to cum."
You stomp the round then roar, making your presence known. You need release, and these humans will give it.