Horizon stood hesitantly outside of Chestnut’s house. Hovering beside him was a note, clad in the bright green glow of his magic. It was this note that had prompted the visit along with the trepidation in his eyes.

It read:

Horizon—

I’ve been working all week on analyzing that sample you gave me. Your magic really is incredible—it rearranges things at a cellular level!

In any case, I think I might have a spell that will let you shrink your “equipment” back down once you’re done using it. It might make things a little less inconvenient for you. If you’re interested, drop by tomorrow afternoon, and we’ll try it out.

—Chestnut

Biting his lip, he lifted one hoof and rapped three times on the door.

Knock, knock, knock—

Not a second after the final knock, the door swung open. A small grin flitted onto Horizon’s face, and he opened his mouth to say hello—

“Who’re you?”

Blue coat, orange mane. Piercing black eyes. A voice that sounded anything but happy to see him.

In other words, not Chestnut.

Horizon did his best to stammer something out—what was going on? had he come to the wrong house?—as the mare stared him down.

“Well? Can you talk, or—”

“Marigold! What are you doing?”

There was a familiar voice. Horizon instantly relaxed as a friendlier face came into view: Chestnut, her mane bouncing over her shoulders as she trotted to the door. A white lab coat hung over her back, and there was a clear frown on her face.

“I told you to let me get the door,” she scolded the other mare—Marigold, Horizon guessed. In a flash, the scowl was gone, to be replaced by a wide, beaming smile as she peered through the door at him. “Horizon! Good to see you—come right in!”

“Good to see you, too, Chestnut,” Horizon said. He stepped through the door and gave her a quick hug.

“So he’s that guy, huh?”

Pop.

Horizon looked up. There was a sticky, pink mess covering half of Marigold’s face. As he watched, she stuck her tongue out and lapped it all up, smacking her lips as she chewed on her gum.

“That guy?” he asked dumbly.

Chestnut sighed, brushing her mane out of her face. Horizon blinked after her—had she been blushing? “Yes. I managed to let slip that I was taking a look at your...problem—”

Marigold snorted.

“—and she all but demanded that I let her come.”

“Demanded? Chestnut, your memory must be going,” Marigold scoffed. “I asked nicely, what with you seeming so excited and all.”

Chestnut shot her a dirty look, but turned back to Horizon with a smile plastered on her face again. “Anyways, I hope you don’t mind. She’s promised not to be a bother.”

“She has?” Horizon asked. He frowned toward Marigold.

She was scowling. Though she was rolling her eyes, she gave a nod nonetheless. “Yeah, yeah. Just get on with it.”

“On with what?”

Marigold popped another bubble and chewed. “C’mon, get your thing out. Your dick. Your wang. Your—”

“I think he gets the picture,” Chestnut cut in, adjusting her glasses. “But yes, Horizon—if you’d like to learn to perform the spell, then we’re going to need you...well, ready. Exposed.”

“And if what half you’ve told me is true,” Marigold said, “then I doubt you’ve got any problem with that.”

Chestnut flushed.

“Hey! Cut it out!” Horizon said. He took a step forward, ignoring the familiar smack of his cock against his thighs as he moved. “What’s got you all stuck up your own ass like this?”

“Oh, he’s got some attitude.” Marigold licked her lips. “I like this one. Maybe I’ll just have to try him out myself. Now, let’s see that fabled ‘Wonder-Cock’ of yours.”

Horizon opened his mouth to reply, but Chestnut cut him off. “All right, all right. Everypony, just...relax, okay? Horizon, I’m going to need you, well—” she coughed—”hard for this. Otherwise, the spell might not take.”

Horizon felt his cheeks color, and his eyes darted back over to Marigold. She was still watching him, eyes narrowed lewdly. She popped another bubble, running her tongue across her lips, and he shivered.

“Okay, then,” he said doubtfully. “And you’re sure that this spell will work as you said? It’s, uh—”

“—reversible?” Chestnut nodded. “It should be. There’s no reason you shouldn’t be able to just use your natural growth magic to set it back. Think of this spell as just...well, folding it away.”

Horizon nodded. Eyes flickering over Chestnut’s form, he took in the curve of her body, her taut, rounded bubble of an ass. Unconsciously, he ran his tongue over his teeth as he remembered that flank in his hooves, his shaft pounding into her depths as he filled her with his hot, steamy—

Horizon blinked and peered between his legs. Sure enough, he felt a heavier weight dangling there. His horn flickered, and the invisibility spell fell away, revealing his massive, churning balls and his swollen, throbbing member.

He chuckled awkwardly, eyes darting back over toward Marigold, who’d retreated to a corner just to watch. She was leering at him—rather unpleasantly, really—and with all of the blood running to his groin, he decided that he might as well give her something to leer at.

With a grunt, he plopped himself back onto his flank. His member came up with the rest of his underbelly, bobbing at full mast and sitting atop his gargantuan balls. A small drop of precum had already gathered at the tip, and he shivered as it fell to the floor.

He looked back toward Marigold—and nearly burst out laughing. The mare was no longer leering; if anything, she looked downright dumbfounded. Too shocked to speak, perhaps?

Horizon grinned. Then again, seeing a two-foot-long cock tended to do that to quite a few ponies, especially when said dong was thicker around than their necks.

“Excellent!” Chestnut said. She licked her lips; Horizon could see the blush rising above her cheeks.

She looked...hungry.

“Let’s get started, then,” she said, coughing. “Time for you to learn a new spell.”

"Are you ready to give it a try?"

Horizon nodded. Biting his lip, he pushed a thin trickle of magic through his horn. It lit up, glowing an eerie green, and he molded it into the shape she'd shown him.

Pop.

With a start, he realized that the magic was gone. The spell had finished: disappeared. With wide eyes, he peered down between his legs.

His monstrous cock, standing proud at two feet in length, and nearly as wide around, stood defiantly above his still-churning balls.

"Good job," Marigold said, leaning against a wall. "Looks like it worked wonders."

"I don't understand." Chestnut took a step forward, frowning. She reached out and laid a hoof on the tip of Horizon's flared cock; he nearly shuddered with pleasure at the touch. She felt so warm, so soft—

"It should have worked," she said, frowning. "What went wrong?"

"It's alright," Horizon assured her. Truth be told, he almost felt relieved. He knew perfectly well that the spell would have been reversible, but he had to admit that he'd become used to that heavy weight between his legs. Without it, he would've felt completely off—

"Wait!"

Eyes going wide, Horizon and Chestnut stared down at the former's giant cock. Sure enough, it looked like the tip had receded a bit; as Horizon watched, a shimmer of green light ran down its side, and his dick shrank a bit more.

"It worked!" Chestnut cried.

"It did," Horizon said.

Wow. This felt...weird. His formerly twenty-four-inch dong was now barely eighteen, and it looked to be still shrinking. He felt a pulse of warmth on the tip of his horn, and with a start, realized that the spell was still active.

It hadn't died. It'd just needed a few moments to get started.

Sixteen inches. Fifteen. His dick was still shrinking. His libido wasn't going with it, some backward corner of his mind noted with a shrewd little snicker. His balls had gotten smaller, looking more like grapefruits than basketballs, but it seemed that his body had accustomed itself to a certain level of...stimulation. A few more drops of precum leaked from Horizon's tip as he hit fourteen inches, still going down.

Not a moment too soon, Horizon realized that he'd reached—and passed—a foot in length. His cock looked much smaller—though it was certainly larger than many other stallions' endowments—but he couldn't bear the thought of going back to his feeble seven inches.

Feeble—a few months ago, he would have laughed at the idea. Yet all the same, with another flicker of magic and a grunt of exertion, the shrinking stopped, the glow of magic fading. He stopped with just over ten inches of thick, stallion meat remaining, panting from the effort of the spell. It might not be enough to pierce through a mare and come out the other end—he could feel his boner throbbing appreciatively at the thought—but it was a more-than-respectable size.

If he had to make himself smaller for convenience's sake, it might as well be with a size that he could live with.

"Well," he heard from beside him. He was still staring intently at his cock, watching as the last flickers of magic vanished into the air. "That's one way to shrink a cock. But I think you forgot something."

Horizon blinked—and then noticed the two grapefruit-sized nuts sitting between his legs. Even at their reduced size, they were still large enough to push against the sides of his legs, and the size differential between their width and his shrunken cock looked almost freakish. Blushing, he quickly whipped out the spell again—it came easier this time, more naturally—moaning as he brought his two testicles back down to size.

Marigold smirked from her place in the corner. "You got there in the end," she cooed. "Looks like Mister Big-Dick ain't so big anymore."

"Oh, I don't know," Chestnut said, elbowing her. "He still looks pretty nice to me." She licked her lips.

Horizon chuckled and flashed Chestnut a smile. It was true that his cock was nothing to laugh at—even at less than half its previous size, it was definitely a dick to be proud of. Getting back to his hooves, he stumbled slightly and overbalanced.

Chestnut caught him with one of her forelegs, keeping him upright. "You okay?" she asked.

Horizon flashed her a sheepish grin. "Yeah," he said. "I'm just used to having more, uh, weight there, I guess. I'll get used to it."

Shclick. Schlip.

Wet, smacking sounds echoed through the room. Horizon blinked, meeting Chestnut's eyes. She silently shook her head.

He frowned. He could swear that he could hear something dripping as well...

"Mm... That's good..."

"Marigold!" Chestnut said, spinning around on one hoof. "What are you doing?"

The other mare, who had one hoof conspicuously placed between her back legs, looked up and grinned at her. "What? A girl can enjoy the view, can't she?"

"But—"

"You said it yourself—it's nothing to sneeze at. And besides," she added, her voice moving to a lower, more sultry tone as she stared at Horizon with heavy-lidded eyes, "it's been a while since I've had a stallion."

Horizon felt the blood rushing straight back to his groin. Who cared if he wasn't big enough to stretch her pussy to the breaking point, his stallionhood seemed to be asking. He could see the puddle forming beneath her dripping marehood with each stroke of her hoof, and could smell her scent, intoxicating in the stale air of the house, filling his lungs with each new breath.

He swallowed, trying to look a bit less flustered. "I, well—"

"What's wrong, 'big boy'?" Marigold purred. She removed her hoof—still dripping wet—and took a step toward him, flittering her eyelashes. "If I'm to believe half the tales going around the farm, there's no way you haven't seen a mare before. Especially not with what this naughty little filly's told me." She nodded toward Chestnut, who blushed an angry red.

"Not that I would mind," Horizon said quickly. "I...are you sure?"

Marigold licked her lips: sensually, running her tongue across her mouth slowly, deliberately. "Oh, like I said—it's been a while. And you're still a good enough size to stretch me just as much as one of my toys."

"I really should have expected this," Chestnut muttered, hoof on her forehead.

"So what do you say?" Marigold asked with a wink. "You up for some playtime?"

"I—" Horizon's word hung in the air, but he bit his lip and nodded firmly. "Yes."

A cheeky grin split his face in two. "The question is, are you ready for me?"

Marigold threw her head back and laughed. "Oh, I like that—a stallion with some backbone."

She smirked back. "Now, let's get a taste of that sweet-looking stallion meat."

"I—" Horizon began, but Marigold was too close, too aroused, and his dick too well-displayed to stop her in time. Her tongue ran across her lips, and in a single fluid motion, she bent down before him, his ten-inch member throbbing appreciatively at her touch.

He shuddered as she took him roughly in her hooves, his hips jerking involuntarily at the contact. A thin line of saliva dripping from her mouth, Marigold met his eyes. There was a hungered, crazed spark there—and without another moment's hesitation, she dove down and took him into her mouth.

A long sigh escaped from his chest as her moist cheeks descended around his stallionhood. It felt...strange, really to be so small. He needed to be filling her mouth, pushing her jaw so far apart that it would crack—but here she was, fitting his flared head easily into her mouth as her agile tongue lubed up the sides, swirling around his length. He groaned, eyes fluttering as her hooves played roughly with his balls.

With a wet-sounding shclick, she slid off the top of his cock and grinned up at him with heavy-lidded eyes. "Mm. You liked that," she murmured, "didn't you?"

Horizon nodded. His sensitive member gave another twitch and he whimpered as a line of saliva dripped down from his tip.

"Mm," Marigold said again, that glint returning to her eye. "Let's get you all nice and lubed up, shall we?"

And with that, she descended again onto his cock, fitting a whole five inches in her mouth—a full half of Horizon's new length. Horizon grunted, feeling her eager tongue lapping around his medial ring—and then moaned loudly as Marigold pushed herself even farther down until she was deepthroating his cock.

It felt so good—her movements were jerky, her motions sloppy and without finesse, but something about Marigold's roughness just set him off to no end. In the corner of his eye, he could just barely make out Chestnut standing against the wall, her own hoof rubbing madly against her clit as she bit down on her lip.

Horizon squirmed as Marigold went up and down his cock, taking every inch in and pushing it back out of her mouth before shoving it back in. It felt intense—she was squirming, pushing on top of him as she deepthroated his length.

Somewhere in the back of his mind, his pleasure triggered something. He wasn't entirely aware of it, but as he moaned for the next time, Marigold's lips bumping up against his swollen balls, a thin sheen of green light shimmered across his horn.

It was a few moments before Marigold realized that she was getting more of a mouthful than she'd expected. Horizon's cock felt more...solid than when they'd started. Fuller.

One might even say that it felt...bigger.

Just as she was about to poke her head back up to make some snide comment about his ego, she felt a pressure on the back of her neck. Horizon had wrapped his two hooves around her head, and with a single, powerful motion, forced her back down until her lips met the base of his stallionhood. She sputtered for a moment as his ring forced its way through her lips, his balls brushing against her cheek as she turned her head to the side.

The green glow intensified, and with a single, horrifying thought, Marigold realized that Horizon's cock was growing—and it didn't seem to be stopping. Fourteen inches now if it was an inch—there was no way she'd be able to remove herself now, not with his girth pushing against the sides of her jaws and his hooves on the back of her head.

It swelled even further as his hooves forced her down, and she sputtered again, her drool speckling the top of Horizon's sack. She was choking on his cock; its girth was so wide, its length so enormous, that it'd become lodged behind her tonsils, the very contractions of her throat masturbating him with a warm and moist touch.

Horizon moaned as a generous spurt of precum spurted from his tip, falling straight into Marigold's stomach without any resistance from her mouth. His member filled her entirely, choking her with pure size.

The orgasm was coming. He squeezed his eyes shut, his member growing until it was nearly a foot and a half in length, and with every single inch squeezed inside of Marigold's choking throat.

With a cry of pleasure, he felt the orgasm strike him, like a bolt of lightning running up his spine. Pints of cum exploded from his tip, running through his swollen, flared head and exploding past Marigold's tonsils and down into her stomach. She let out a muffled cry, squirming beneath his grip as each new cup of spooge entered her stomach, filling her and producing a small bulge.

Panting, Horizon felt his orgasm end. His cock had already begun to wilt with the end of it, his hardened member receding until it gave Marigold barely enough room to breathe. She choked—coughing, even louder, until she spat his length from her mouth, wheezing in the warm air.

"What the fuck," she spat, "was that?"

Horizon's eyes were still closed, but as he cracked one open, he noticed his hooves clasped around Marigold's head and his massive cock resting against her chest. "Oh, gosh," he began, eyes going wide. "Marigold, I'm so sorry—I never—"

"That," she said, eyes reddened, "was—"

She paused and coughed one more time.

"The hottest fucking thing I've ever felt."

Horizon startled. "Wha—?"

Marigold was beaming, a few lines of saliva still running down her cheek and mixing with lines of his seed. "That was fucking intense," she said. "That fucking cock, I swear—I choked on that thing! And this is as big as it gets?"

"Bigger," he admitted sheepishly. Marigold looked at him in astonishment before a wicked grin crept over her face.

"Well, then," she said with a smirk, putting her rounded belly. "We'll just have to try another hole, then, won't—"

"Oh!"

Both heads turned to face Chestnut, who by now was slumped over the floor, hoof pushed firmly against her marehood. Her eyes were wide, her mouth hanging open, and her hooves shook as the orgasm took her. Horizon's nose twitched, and he felt another surge of arousal in his once-again oversized cock; he could almost taste Chestnut's arousal in the air, could smell her desire through the juices that dripped from her pussy.

Chestnut moaned again, her eyes drifting closed as her hoof slapped against her feminine lips. “Oh,” she murmured. “Oh, yes. Oh…”

As the last throes of her orgasm left her, she stopped—blinked—and turned, wide-eyed, to face the other two.

She blushed so hard that her face looked like it was on fire.

“I, oh, my,” Chestnut stuttered, removing her now-damp hoof. “I’m sorry, I just—”

“You liked that, didn’t you?”

Marigold’s smirk spread until it covered her entire face. She licked her lips, meeting Chestnut in the eye. “I’d say just as much as Dick-Colt over here. You were totally perving on us.”

Chestnut nodded mutely.

Marigold licked her lips, a glint in her eyes. Before anypony else could react, she’d pushed herself forward—

—and landed right with her mouth right over Chestnut’s.

Chestnut let out a yelp before giving into the kiss. Marigold’s weight pressed down over her, and she could feel her rounded belly pushing into her own, still able to hear Horizon’s cum sloshing around inside.

Marigold ground her snout into Chestnut’s, taking in her scent. She probed outward with her tongue, poking into the inside of Chestnut’s mouth.

Chestnut moaned, shifting beneath Marigold as their tongues met, dueling as saliva dripped between their mouths. Her marehood, still dripping wet, rubbed against Marigold’s leg as the latter ground her own clit into Chestnut’s stomach. Marigold’s pussy, still wet with arousal, dripped over Chestnut’s coat, soaking into her fur.

Back on the other side of the room, Horizon watched the exchange with wide eyes—though certainly not with disapproval. His hoof ran up and down his own length, almost unconsciously, as his monstrous cock stiffened back to full height. The magic returned, his dick growing with each new stroke of his hoof, until it had reached two full feet of stallion meat once again, his gigantic balls churning with seed beneath him. Slowly, tenderly, as Marigold shifted her weight and buried her snout in Chestnut’s clit, Horizon leaned over and gently licked a thick clump of cum off of the tip of his cock. It tasted salty, and he shivered with pleasure as he swallowed his own seed.

His eyes drifted over to Marigold’s taut, rounded flank, and he felt his returning boner throb in appreciation. Maybe…

Chestnut was in high heaven as Marigold’s tongue probed her marehood, invading her every nook and cranny. Sweat beaded on her forehead, and her own tongue hung out of her mouth as she panted in pleasure. “Oh, goodness—more,” she moaned. “More, more, more!”

Marigold, evidently, was only too happy to help. “Mm,” she grunted, kissing Chestnut’s marehood on the lips before going back to ravaging them. “You taste...delicious.”

Her eyes widened as she felt a sudden pressure against her rear end. She didn’t stop licking Chestnut’s moist cunny, but her eyes then narrowed all the same.

That same weight prodded against her behind once again, and Marigold recognized that familiar feeling of girth. She could feel two orbs pressing against the backs of her legs, could hear that slight whimper that escaped from behind her.

“So you want your turn with the other end?” she said, pulling up from Chestnut’s crotch and wiping her lips.

Horizon grunted from behind her.

“Then go ahead,” Marigold murmured lustily, looking Chestnut right in the eye. “Fuck me crazy. Let’s feel that godlike cock of yours.”

She dove in for the kiss, her tongue intertwining with Chestnut’s—and Horizon took the initiative.

He was slow at first, gently pushing his enormous head between Marigold’s legs as she squirmed on top of Chestnut. Yet, for whatever reason—perhaps she was loose from other stallions, or simply too many nights spent alone with her own “toys”—she was loose enough that he could fit the entire head in.

Horizon grunted as he entered her marehood, feeling her pussy juices dripping down his throbbing member. The feeling was so electric that some corner of his mind reacted instantly, a green light flickering over his length as he slowly drove his cock deeper into Marigold’s pussy. His member expanded even further, his oversized balls all but screaming with horniness, with a need to spill their seed inside of this amazing, fuckable mare.

On and on his cock grew, twenty-five, twenty-seven, thirty inches—until it was poked right up against Marigold’s cervix, with an entire quarter of his cock still left outside.

In and out he thrust as Marigold and Chestnut dueled, their mouths locked together in a neverending embrace. Flesh smacked against flesh as Horizon fucked Marigold silly, his enormous member going so far in as to leave her stomach bulging with his sheer size.

Marigold had never felt so full. Horizon filled her completely; as she looked down, she could see her stomach rounded even more. Watching her swelling belly, her eyes widened as that bulge disappeared—and then pushed forward again. Horizon grunted behind her, and she moaned.

“Oh, fuck,” she bit out, pulling away from Chestnut before the latter hungrily seized her head and pulled her down once more. “Mm. Oh. Mm.”

It felt like nothing she’d ever felt before. She pushed against Chestnut, grinding her lover’s pussy beneath her hoof. She could feel the heat between her loins intensifying, her arousal peaking to insane levels. Jolts of electricity began to sizzle up her spine, preparing her for the bursting orgasm that was to come.

Horizon’s eyes rolled up into his head as he fucked her like a cocksock. In and out, flesh smacking against flesh—her tender, abused ass filled his vision entirely, making him hornier than ever. His balls grew until they rested on the floor, his cock growing a few more inches until the bulge refused to disappear from Marigold’s stomach. He groaned, biting his lips as he felt the tension building—

“I’m—”

Marigold moaned. “—cum—”

Chestnut let out a cry of pure pleasure. “—ing!”

All three came at once, their orgasms striking them like bolts of lightning right down the spine. Chestnut’s pussy flooded with juices, her femcum dripping down onto the floor and drenching Marigold’s hoof.

Marigold’s back arched as hers hit, the fire in her thighs burning up until it held her entirely. She drove herself down with an enormous intensity, licking, biting, kissing every inch of Chestnut’s body as she rode the orgasm, pulling it out to a fiery, burning finish.

Horizon’s eyes nearly rolled back into his head, his hips rolling and bucking as his seed spilled out into Marigold’s womb. He flooded her pussy, her cervix, coating every cubic inch of her insides with his warm, sticky seed. Her belly bulged out from his monstrous cock before flooding out even more with his gallons of cum. His balls churned between his legs as her stomach expanded until Marigold looked pregnant with foals. She let out a cry, fuller than she’d ever felt before, as Horizon thrust again and again, filling her until his warm spooge leaked out of her marehood and onto the floor, leaving a sizeable puddle behind.

“Oh,” Chestnut moaned. “Oh, Celestia. Oh, Celestia.”

Slowly, waiting as his cock spurted out a few more thick ropes of cum, Horizon pulled back out of Marigold, leaving her to collapse onto Chestnut’s warm body as her own distended stomach squished and jiggled beneath her.

“Oh, fuck me,” Marigold moaned. “That was…”

“Amazing?” Chestnut offered.

“Intense?” Horizon murmured, gazing at his enormous, two-and-a-half-foot cock.

Marigold turned to look at him with heavy-lidded eyes. “Got it in one, dickboy,” she whispered. “Fucking intense. Intense as fucking Tartarus.”

Another shiver of pleasure ran up Chestnut’s body, and she struggled to pull herself to her hooves. “...My,” she finally said. “I never expected that.”

Horizon chuckled weakly, getting to his own hooves. “I probably should have. It seems to come with the package.”

Marigold smirked at him. “Package? That was a terrible pun.”

She looked down and slapped her rounded belly, which was bulging with gallons of his seed. “So this is what fucking you does to a mare, hm? Let’s see how long it takes before I can walk this off.”

Chestnut snickered. “Good luck with that.”

“Watch me.”

Marigold turned to face Horizon, a genuine smile tugging at one corner of her face. “Come back ‘round any time,” she said with a wink. “I’ve never gotten fucked like that before.”

Horizon nodded dumbly.

“Now, if you’ll excuse me,” she went on, eyeing Chestnut hungrily, “Miss Science and I have some...washing up to do. Let’s hit the showers, hm?”

Chestnut shivered as Marigold ran her tongue across her lips. “Oh,” she said quietly. “Oh.”

Horizon could take a hint.

As he got up to go, doing his best to brush off any clinging fluids, Marigold turned around and gave him another wink. “Oh, and lover-boy?”

He paused.

“There’s a party going on tomorrow night at the bar in town. Something tells me you might want to hit it.”

A grin spread across Horizon’s face. A green glow spread out from his horn, shrinking his package back down to a more manageable size. He turned to beam back at the two mares.

“Something tells me,” he said, grinning like a foal, “that you’re right.”

He winked back. “I’ll be there.”