His body seemed to explode with strength, muscles swelling beyond any reasonable limits as their fibers were drenched in your power. Every single one of his bones cracked as his skeleton was remade larger, thicker and stronger, now easily dwarfing your dainty form. He grunted in a deepening voice as his abs popped out from his stomach, a glorious 8-pack being forged.
His dick was completely engulfed in your vagina as you orgasmed, and thus it got a full-force blast of your power, swelling larger and larger within seconds. Your previously tight vagina ran out of room in seconds as his manhood remolded it around itself, bursting through your cervix and tickling your womb. His balls fizzled and bulged as they inflated to the size of oranges, about to burst from an overabundance of cum.
But the metamorphosis of his body was nothing compared to the transformation of his mind. Previously he stated that your enhancements felt like a new lobe growing on his brain, but now that was physically becoming a reality, his brain literally splitting apart as his two lobes became four, unlocking previously unattainable processing power. With that, his powers drank in your energy and evolved, his Suggestion becoming straight mind control. He could now force anyone to do as he pleased, and even alter their thought patterns.
He screamed, both in pain at this incredible mutation and delight over his growing influence. His IQ skyrocketed as he drank in more and more energy, his brain processes running faster than ever before, the four lobes interfacing with each other seamlessly.
As his IQ reached the 300s, another shift happened, and his brains grew a new gland. Soon enough objects around the room began to float around due to his newly discovered telekinesis, and he found he no longer needed to keep a hold of Wellspring. His evolved mind did it for him, his control and power growing alongside his brain matter. The number of controllable things grew, as well as their size and weight. Previously he was only locked in this room, but he could feel his power quickly reaching outside of it. This included his mind control and telepathy, and he could soon enough sense individuals that were dozens of meters away, easily slipping into their minds and taking full control over their functions.
This was too much for him, and his overwhelming growing power caused him to go over the edge. With a mighty grunt and a maniacal yell, he released his load, flooding your womb with cum. You choked as you felt his huge manhood unleashing a torrent of baby batter into your sacred place. It actually bulged your stomach, his huge dick acting as a seal preventing any from flowing out. It felt like even your ovaries were swimming in the stuff.
"Yes, YES! My dear, you have transcended me! Even now my power is growing as you're feeding it! Soon this entire city will be mine, and then the world! Nothing can stop me, and it's all thanks to you! AAAHHAHAHAHHAAAA!!!" He laughed, relishing in his newfound power.
You collapsed on the bed as his telekinetic hold let go of you. You had no strength left. He had drained you. Only a small spark remained, and that would take forever to recharge. You were utterly spent, and truly at the mercy of the monster you had created.