You win by a landslide

It takes Faust a few moments to process what just happened before his face is slowly overtook with horror. Serves him right for underestimating you

"WAIT, PLEASE, LET'S TALK ABOUT THIS". As you feel the spell starting to take effect, you get to watch Faust lose his composture for the first time, loudly pleading for mercy at your feet as you open your robes to better acomodate your soon-to-be monster cock

However, you can't help but noticed that while he begs for you to wait, his erection has risen to a full mast...

It's your turn to tease him. "What's this? Don't tell me the big and powerfull Faust is enjoying having his dick drained?". His dick twitches in response. He tries to deny it but is interrupted by his own moans of pleasure as the process begins. You can't balme him, it feels orgasmic

With each beat of your heart you feel yourself getting bigger, each growth spur acompained by growing pleasure. It's amazing, makes you feel like you never really had a full erection before, your dick and balls getting bigger and bigger as Faust's shrink down

As the spell reaches it's end, so does Faust, shooting smaller and smaller ropes of cum as his once-magnificent cock is reduced to the bare minimum one could call a penis. You quickly follow, covering the nude demon with thicker and thicker ropes of cum as your transformation is compleated

Looking down you take a moment to apreciate the view. Your fully erect penis is even larger than what Faust had, standing at well over 18'' long and 3'' 1/2 in diameter. The cum-covered demon in front of you thou, displays a pathetic 1'' knob, thinner than what you thought possible.

Still fully erect thou...