While Gabe was still napping, Mary untangled herself from her girlfriend and crept over to the vials. The challenge of 'filling up' Gabe, and her pussy sucking her dry rang clear in her head. But to survive that, she'd need something a bit stronger. She grabbed the Muscle+, Size+ and Dexterity+ vials, mixing four doses from each of them into two vials.
The first went straight into her cock. Mary gasped as the long appendage grew even longer, doubling in length from three feet to six, then even longer. Her eight-foot cock, larger than her body, slithered on the floor like some grotesque, fleshy boa constrictor. It hadn't gained much girth, either, just the width of her calf. But that was soon to change as the muscle kicked in. It swelled with vascular tissue and thick, steely muscle fibres, veins running down the side, each second even more over-bloated and grotesque. The dexterity too began to take effect, and Mary writhed the huge, thick appendages at impossible angles, tying her cock in knots as it swelled larger than her already huge body. By the time it was done, it looked less like the cock was attached to her, but rather she was attached to the gigantic dick.
Mary wrapped her utterly monstrous cock around herself until the pumpkin-sized head sat on her shoulder. She gave her organ a few pats before sliding the vial into the apple-sized cumslit. Her dexterous cock fondled and massaged the tube down, careful not to pull out the cork nor shatter the glass before it reached its destination. That being her six balls, of course. The contents were expertly divided and delivered, each of the bumps churning as they accepted their potent gifts.
Mary doubled over, wrapping her arms and cock around her middle as her testicles groaned and clenched. They began to expand, growing apart even as they pressed harder against each other. The little lumps were soon six bowling balls that decorated her abdomen. The huge mounds grew more defined, sharp, muscular mountains of powerful, leathery flesh. As the dexterity came, Mary found herself gaining complete control over every minute movement, able to squash and pull them in at a moment's notice, but also able to fold them in on themselves and feel every single sperm inside them. As she began to pump them, flexing each one rhythmically like huge pistons on the machine that was her mammoth cock, a loud thud resounded with each movement. They were so large and so heavy they sounded like a combustion engine, growling and purring as Mary made them twitch.
As she did, she could feel a want to expel her sperm, to breed, and even though she wasn't close to orgasm, she knew with her new musculature and dexterity, cumming without any stimulation wouldn't be an issue. However, Mary did not want to release just yet - her loads were promised to Gabe, after all - but it did give her an idea as to what she would enhance next. She grabbed the box of vials again.
This time, she chose four doses of Liquid+, three of Muscle+, and two of Strength+ and Magic+. Combining them into one swirling vial of shimmering red, she swallowed it all the way down to her balls. But, with the new control over her testicles, she wouldn't allow them to coat her muscles, no. Instead, she kept it only touching her sperm.
Instantly, she could feel the Liquid+ take effect, as her balls bloated even larger with a huge increase in her cum production. Once bowling balls, they became watermelons audibly sloshing with each rhythmic thump and churn. Inside her balls, a greater change was taking place.
Her sperm, once tiny, began to increase in size, growing beyond microscopic to the size of tadpoles as they bloated with super dense muscle. Strength kicked in, and Mary could feel them swimming around in her sac as they grew strong enough to break through concrete and steel alike. And, of course, the magic. They soon were able to multiply without any need for fluid, an infinite source of sperm that wouldn't drain Mary's reserves a bit. No refractory period would keep her from coming now. Her seeds could take root in any organism they wanted and would seek out fertile eggs in any form, sensing any potential recipients and not letting anything stop them from reaching their target. They were unstoppable, unkillable breeding machines that would make sure Mary's lineage would live forever.
As the transformation ended, Mary smiled and placed a hand on her huge, full, pumpkin-sized balls, feeling her sperm press hard against it. Flexing, she allowed a few to escape, watching as the tiny white monsters burrowed straight through the floor and were released into the world. Absent-mindedly, she wondered what her children would be, half flower, perhaps? Or maybe the sperm would find a rat or spider to impregnate. Either way, she was a breeding machine made for fucking and fathering, and she grinned happily as she made her balls thump back their agreement.
"Mm, Mary? Whaaa-" Gabe was quickly silenced as she awoke from her nap by the huge, thick python that was Mary's cock wrapped around her and lifted her with ease. She struggled against her musky coils, but to no avail - Mary's member was simply too powerful. Her mouth was filled with a tongue of muscle as Mary used her extreme dexterous control to French kiss her girlfriend without loosing a single coil.
As Gabe hung there, Mary could feel her pussy trying to fight back against her sudden dominance. She clucked her tongue and mixed a vial. "Ah ah ah, I don't think you're in control anymore, Gabriel. But don't worry, I'm going to make you feel better real soon..."