Back at Canterlot castle.
"Master," Viktor said, as he and his team entered the throne room, "we have return with the crystal."
"Excellent," Zs'Skayr, still inside Luna, smiled, "now my plan can complete."
"Would you mind letting us in on your plan?" Albedo asked.
"You watch your tone!" Viktor thundered, purple electricity erupting from the conductors on his back, "this is Lord Zs'Skayr your talking too, we're to serve his every whim and like it."
"Thank you, Viktor," Zs'Skayr said, "but Albedo is right, I've kept you all in the dark for far too long."
"It is good that you think of us all as equals," Albedo replied, "So why are the Corrodium crystals so important to you?"
"Ever since I entered this dimension I had my sights set on spreading my nightmare across the multiverse," Zs'Skayr continued, the Mummy presenting the crystals to him, "and with these crystals I will be able to infect each and every dimension."
"How are we suppose to jump dimensions with only three crystals?" Bad Ben asked.
Zs'Skayr, using Luna's magic, made the crystals multiply, "Now we have what we need," he smiled.
Albedo shared Zs'Skayr smile, he slapped his omnitrix and transformation into Ultimate Albedo.
"Viktor, you will assist Albedo with the construction," Zs'Skayr ordered.
Viktor nodded and with that he and Ultimate Albedo carried the Corrodium crystals to begin construction on Zs'Skayr inter-dimensional teleporter.
Back at the Castle of Friendship
The Nullvoid team had returned with Princess Celestia, after Twilight and OV Ben had explained why there were multiple versions of Ben and the Elements, they were now working out a plan.
"I say storm the place," Other Ben 10,000 suggested.
"I'm all for the direct route," Vinyl agreed, Rainbow Dash, Rainbow Blitz and Fire Dash nodding in agreement.
"Because thats what Zs'Skayr will be expecting us to do," Ben 10,000 replied, "we need to do something Zs'Skayr and his forces won't be expecting us to do."
Like what?" Other Ben 10,000 retorted.
"A plan that doesn't result in disaster," Ben 10,000 answered.
Seeing that a fight was about to break out OV Ben intervened, "How's the other Fluttershy?" he asked.
"Flutterbat," Rarity corrected.
"Whatever," OV Ben replied, "and also how did that thing get created?"
"I have a theory," Twilight said, "You said that Corrodium crystal's energy mutants all earth based species,"
"Yeah," UA Ben replied.
"So when Fluttershy tried to resist, somehow it caused the crystal's energy to backfired," Twilight continued, "It took the evil fruit bat side of Fluttershy, separated it from her psyche, and made it into its own being."
"That doesn't explain why she acts like an animal," Fluttershy stated.
"Well, why best guess," UA Ben continued, "without Fluttershy's guiding intelligences Flutterbat's nothing but instincts."
"But she is showing signs of devolving intelligence and self awareness," added Ben 10,000.
"Anyway what did you do with her?" Lyra asked.
"Oh, we just tied her up and locked her in a storage closet," Time-Turner answered, "She'll be fine."
"We're getting off topic here," Derpy interrupted, "We need a plan before we do anything."
"Twilight is right," Celestia nodded, "with Zs'Skayr in control of Luna it will take everything we've got to take him down."
"Then we need a plan of attack," Rook agreed, "we need to do something that Zs'Skayr and his force won't be expect."
"Rook's right," OV Ben said, "Zs'Skayr expects us to rush in swinging, but what if we snuck into his base."
"That might work," Starlight replied, Rarity, Elusive and Trixie agreeing with her.
"We'd have to get someone into Zs'Skayr's base no one would suspect of being a spy," Trixie added.
"I could do it," Thorax spoke up, "I can impersonate one of the evil elements,"
"With what we're going to need more then just one person on the inside," Starlight Sparkle stated.
"The only four aliens that would be good for stealth are: Ghostfreak, Nanomech, CamAlien and Big Chill," OV Ben answered.
"What if we pretended to surrender," Twilight suggested.
"That might work," Ben 10,000 replied.
Back to Canterlot castle
"Master, the enemy have announced their surrender," Viktor said, kneeing before Zs'Skayr.
"We won," Plunder Pie laughed, "that wasn't so hard."
"You don't really believe that, do you?" Mad Ben asked.
Zs'Skayr laughed at that, "The fools think they are hunting me, but the hunters shall soon become the pray."
Back to the Castle of Friendship
"Everyone remember the plan?" OV Ben asked.
Everyone and everypony nodded.
The door to the castle burst open to reveal Bad Ben and Twivine, "knock, knock." Bad Ben snarked.
OV Ben and Twilight turned towards the two doppelgangers, "Take us, but leave the others alone" Twilight said.
"Sure, you're the only two the boss wants," Bad Ben replied, OV Ben and Twilight joined the two and teleported away.
As soon as they had left Ben 10,000 turned to the rest of the team, "OK, team lets move."
Canterlot castle
"Did you miss me Tennyson?" Zs'Skayr laughed, as he looked down on two heroes.
"If I say yes, will you please pop a mint?" OV Ben asked.
"Your pithy quips and clever observations won't save you this time," Zs'Skayr replied, he turned to Twilight, "and you Princess of Friendship, neither you nor your friends will stand in my way."
"These's something you should know about my friends," Twilight said, there was a flash of green light and where Twilight had been standing stood Thorax, "we never give up without a fight." Thorax finished.
Just after Thorax said that the sound of Rook's Proto-TRUK approaching the castle could be heard.
"Everyone, defend the castle!" Zs'Skayr barked.
"I know this was a trick," Mad Ben said, as he, the other evil Bens and Elements, The Mummy and the Werewolf rushed out to defend the castle.
"How is the construction going, Viktor?" Zs'Skayr spoke into a communicator.
"The construction is proceeding ahead of schedule," Viktor's voice replied.
"When you have finished, you and Albedo must defend the castle, we are under attack," Zs'Skayr barked.
"By your will my lord, it shall be done," Viktor responded.
"Thorax go help the others," OV Ben said, "I'll hold Zs'Skayr off." he slapped his omnitrix and transformed into alien mummy, Snare-oh.
Thorax obeyed and dashed out of the the castle.
"Now we finish this," Zs'Skayr smiled.
The two engaged.
Outside the castle.
"Alright," Bad Ben said, he and the other evil versions waited for the heroes to attack, "we're going to hold the line," he slapped his omnitrix and transformed into Four Arms, "and block the castle gates." he finished, cracking all four of his knuckles.
The other evil Bens, apart from Eon, followed suit: Mad Ben into Waybig, Nega Ben into Shocksquatch and Benzarro into Spidermonkey.
The good Bens, along with the Elements, readied themselves.
UA Ben transforming into Waybig
Ben 10,000 transforming into Atomdrillo (a fusion of Armodrillo and Atomix)
Gwen 10 morphing into Rath
Ben 23 transforming into Techno-bubble (his universe's version of Upgrade)
and Other Ben 10,000 activating his Ultimate Ben (equipping himself with Water Hazard's powers.
"It's time to taste the bass," Vinyl said, she put on her shades and pulled out her Bass Cannon.
Techno-bubble merged with Vinyl's Bass Cannon and transformed it into a battle suit that form around Vinyl.
"Yeah, let's party," Vinyl said, admiring her Bass Battle suit.
"I agree," Waybig replied, "It's time to go ultimate." with that he slapped the Ultimatrix symbol and transformed into Ultimate Waybig.
Both the heroes and villains clashed.
Ultimate Waybig and Mad Waybig grappled with each other and shooting their cosmic rays.
Vinyl rushed around in her battle suit dishing out blasts of wubs and music at the villains, "Woo, you feel that?" she asked, as she blasted evil Spidermonkey with a huge blast of wub energy.
"Yeah, I'm feeling it!" Other Ben 10,000 replied, as he blasted evil Shocksquatch with water, turning his electricity on him.
"Is that all you've got?!" Rath said, as she dodged Evil Fourarms attacks, while also throwing her own punches and strikes with both her fist and wrist blades.
All the evil Elements ganged up on Atomdrillo, but the alien simply struck the ground, creating an atomic shockwave knocking all the evil Elements off him.
"You think you guys can carry on without me?" Twilight asked, while fighting off Brutilight.
"We can take them," Vinyl replied.
"Starlight, you're in charge," Twilight finished.
Before Starlight could answer Twilight teleported away.
"Be careful Twilight," Starlight murmured, she was quickly distracted by Twivine firing on her.
The battle raged on.