How about my previous story idea that last time about King Sombra transforming the Mane6 into his huge penis and aged-up!Spike and Shinning Armor into his huge balls.

“Do your worst!”

Sombra glanced down amusedly at the blue pegasus. She’d been laid prostrate at the foot of his throne, her muzzle just inches away from him. Then he turned to the stallion who’d spoken - the little upstart who’d thought he could steal the King’s throne. He was still defiant. Spunky, even.

An idea came to the king’s mind. Spunky… Yes…

“I could do my worst,” he said, “as you called it. But I think I’ve got something a little more…interesting in mind.”

The pegasus’s eyes widened as the king’s member popped out of its sheath. Even laying across his legs, soft, it was a good foot in length. His two swollen balls followed soon after, each one the size of a small orange and filled with royal seed.

“Suck,” he commanded. His shaft prodded against her lips. She shook her head, tears beading at the corner of her eyes.

He scowled. “I said, suck.” A lash of shadow smacked her in the rump. When she still refused to open her mouth, he lashed her a second time and forced her mouth open.

His cock shoved its way into her mouth, forcing her jaws apart. Sombra groaned pleasantly as he felt her warm tongue moving against his shaft. “Was that so hard?” he asked. The mare only glared.

His horn flickering with shadow, he lined each of the other mares up behind the first. He made sure to position them so that it’d be impossible to miss the winking pussy of the next mare in line. “If you please me,” he said, “it may in turn please me to let you go. So get licking.”

As the mares helplessly got to work, Sombra levitated the two males of the party - the “spunky” stallion and a large, young drake - toward him. He settled them before his throne, one on each side of the pegasus. He grinned down at them. “I will enjoy this.”

Then, summoning up his magic, he got to work.

This wasn’t a dark spell, per se, but it was by no means light magic. Forced transformations had never been favored by the uptight mages that the Empire had hosted before his ascension. Sombra moaned softly, his hips shifting slightly as his cock and balls grew warm. His horn flared and the two males found themselves cheek-to-testicle with his balls.

Sombra began to pant. The mares before him seemed to notice the change, and were now grunting in fear and confusion as the magic around them stiffened them into complete immobility Sombra let his head roll back onto his shoulders, his tongue hanging out of his mouth, while the spell took hold.

The mares below him started to melt together, their skin shifting, flowing, melding together. Each mare’s eyes opened wide, their muffled grunting becoming louder and louder.

But it was no use. Starting with the pegasus attached to his crotch, the .jet-black color of Sombra’s member began to spread across their coats. Their bodies twisted, shifted until they were smooth, veins extending from the first to the last.

Sombra smiled as he watched the largest of the group - the orange one - melt away into the others, her generous hips reforming into his bulging medial ring. Finally, the lips of the blue pegasus melted into his groin, her muzzle warm and gooey against his crotch - and then it was gone.

An enormous, twelve-foot cock, as tall and wide as a pony, extended all the way from Sombra’s crotch, down the steps of the throne, to the floor. He grinned as he watched the fear and rage quivering in the young drake’s eyes.

“Delightful.” He tasted the word, swilled it around. “But with a shaft so wonderfully large, I’ll need a pair of balls to match.” And he summoned up the magic once more.

This time, he groaned even louder while the spell set to work reforming the stallion and drake’s bodies. It curled them into spheres, forced them into the fetal position before melting away their limbs and smoothing out the edges. The same jet-black color spread across them like a virus, and soon, nothing was left of them but a pair of five-foot-tall testicles, each one churning with a veritable ocean of seed.

“Mmff.” Sombra closed his eyes and massaged the base of his gigantic shaft gently. “Marvelous. Now…”

He grinned as he watched his massive cock begin to harden. He could hear the spooge churning in his balls’ depths. “…let’s see how spunky you really are.”