Two days after retrieving the BLU Intelligence and their intel on them…
"Come on, let's move it!", a young male voice said.
At a rocky hillside, Rainbow Dash with Spike on her back, both of them in their 'mercenary' gear, was fleeing from a barrage of rockets. Already, both have been injured and were on their way back to the line 'held' by the rest of the team. However, two key members were missing and without them they would soon be overrun from the rockets exploding around them.
"Come on, come on, almost— Augh!" Spike was cut off by a rocket blowing up right behind them, forcing them both to tumble forward to the ground as Spike is knocked off of Rainbow.
As both of them got up, Spike was about to turn around to Rainbow to help her up, but she said, "Keep going!" Spike nodded and went on ahead as Rainbow attempted to walk on, but then collapsed. Just as he disappeared around a corner, she then heard a whistling noise, risked a look back, and saw three rockets arcing down towards her. "Sweet Celesti—" She was cut off by the rockets colliding at the ground near her position, sending her flying sky-high and right into a building, screaming and flailing all the way until she smashed face-first into a window pane, breaking it.
"Medic..."
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EqU was at an area reminiscent of Badwater Basin, which was still under RED's control. They had decided to lay low there after realizing one thing; they're still researching the ÜberCharge while RED and BLU have already been using it ever since their arrival. While the EqU team has managed to master counter-strategies for that, the fact that they don't have something that basically amounts to invincibility has begun to become a disadvantage.
They stopped at a building down a hill, where Thenam soon discovered that the place was occupied by RED once, where the RED Medic first tested the ÜberCharge. However, BLU managed to find them and was on the attack. For some reason, BLU had decided to send lots of BLU Soldiers. And worse, EqU's "respawn system" somehow obtained a glitch so that while it still rescues anypony who "dies", they cannot be returned. Thenam was at work fixing the glitch.
Holding the line Spike and Rainbow Dash were headed to were Applejack, Pinkie Pie, Twilight Sparkle, Derpy Hooves, and another EqU Engineer (in the colors of Applejack's older brother Big Macintosh). Both Engineers had their Sentry Guns controlled by Wranglers, and Pinkie was using her flamethrower's airblast to knock back the rockets, standing behind a Dispenser to maintain her ammunition.
As for Rarity, she was backstabbing the Soldiers whilst using the Cloak and Dagger watch to remain invisible indefinitely. 
The knife she was using was the Big Earner, a broken switchblade left permanently unsheathed—effectively making it a stiletto—with three small bands of blood-stained tape wrapped near the base. 
She also had the L'Etranger, a stylish, narrow-barreled revolver with an ivory handle design. Both somehow refill her cloak energy but conversely make her more susceptible to damage by 40 percent, 20 percent from each weapon, but one of them also conversely makes healing a bit faster.
Unfortunately, the 'horde' just wouldn't stop no matter how many she backstabbed.
And she was eventually caught in a rocket blast and 'sent away'. 
As for the whereabouts of Chronicle and Fluttershy? They were inside the building with Jothicu.
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Inside the building, the medical researcher was reading the notes the RED Medic left behind for some reason. Also, with some help from Thenam, two futuristic-looking pods were standing where the gurneys were. And inside these were the two 'missing' ponies, and they were about to be treated with that was required for the ÜberCharge.
"Jothicu, I can hear fighting outside.", Chronicle called from within the pod through its comms system. "I'm not sure if the others can hold the line much longer."
"Well, I just figured out how the RED Medic worked up the ÜberCharge, and I've got the chemicals ready, but then I realized the ÜberCharge involves surgery."
"And how is that a problem?"
Jothicu listed the reasons. "One, I still don't know enough of your anatomy. Two, even if I did, I don't want to violate anypony's innards should it have some effect once you're all back in Equestria. And three, even if I was willing to operate on you, I don't have any tools that can penetrate Spike's dragon scales, and none of us knows Equestrian dragon anatomy."
"Equestrian dragon?", asked Fluttershy.
"Our organization spans beyond the stars. And beyond the stars lie plenty of mysteries, wonders, and dangers, dragons among them. I'll be implementing the ÜberCharge system in a different way." Jothicu walked to the pods and pushed buttons on them. "Instead of overcharging your hearts, this system will—when using the standard Medi Gun—envelop both you and your patient in a protective coat of energy, have both your eyes glow white, and be invulnerable to most forms of damage. You're both still susceptible to knockback, the environment, and stuns. Also, should a Heavy with the Holiday Punch hit you from behind, you're gonna lose focus and break the beam."
"Because it somehow makes us laugh?"
"Yes. To this day, I still don't understand how it works, and the laugh it makes from you is rather scary, you know." Jothicu shuddered as he went back to the notes. "I never heard a laugh so evil."
"Sorry. What are the other effects of this…ÜberCharge?"
"Well, you can spread your beam around multiple patients, giving them all the ÜberCharge, but if they're broken off, the ÜberCharge's effects will linger for one second before fading away. Also, you'll find yourselves unable to help in capturing control points, pushing Payload carts, or picking up the Intelligence. You also cannot activate the ÜberCharge if you're carrying the Intelligence and applying it to anyone carrying it will not give them its effects."
"What about the other Medi Guns?", piped in Chronicle.
"When using the Kritzkrieg, the charge is 25 percent faster. In addition, both of your weapons will glow and a harmless crackle of electricity will emit from them. The patient's weapon will inflict all-powerful triple-damage critical hits. As for the Quick-Fix, the charge is also 25 percent faster, not to mention the first Medi Gun to pull off an ÜberCharge."
"And it heals 40 percent faster, but without the overheal the other Medi Guns do, right?"
"Right." Jothicu then went back again to the pods, this time carrying some small cards.
"And it also helps with keeping up with faster allies and catch up with explosive jumpers?"
"Right again." Jothicu then inserted the cards into slots at the pods. "As for its ÜberCharge effect, it grants much faster healing, and both of you will also be immune to stun effects, slowdown and most forms of knockback. And all ÜberCharge last for eight seconds, by the way."
"Are you done yet?"
"Just about. In the meantime, let me discuss about the term 'medic buddy'."
"Medic buddy?", Fluttershy asked. "What's that?"
"A class that is particularly compatible with the Medic in any offensive or defensive scenario. Typical buddies would be the Soldier, the Pyro (although that's a bit dangerous offensively), the Demoman, and most of all the Heavy." He then looked between the two suggestively.
Chronicle seemed to take the hint and retorted, "Hey. Just because we work great together doesn't mean we necessarily are together."
"Why not? That seems to be the case with the RED and BLU Heavies and Medics. And the Engineers and Pyros too." He turned back to face Fluttershy. "Anyway, these do not make good healing buddies; Scouts are too fragile and aggressive—no offense to Rainbow Dash—but they can prove useful in tight quarters or defensive positions if using the Kritzkrieg. Engineers are defensive and thus won't be needing the ÜberCharge, though you can use it on them while they're fixing up a Sentry Gun while under enemy fire or deploying it in a key offensive position. Snipers stay on the back, though they can use an ÜberCharge in a 'Sniper duel'. Using it on others Medics is not a good idea, unless you're doing the Chain ÜberCharge strategy, which I'm sure you won't be using given…well… And Spies are out of the question as you'll blow their cover."
"That's a lot to remember. But I'll try."
"Anyway, Fluttershy, remember that knockbacks will break the ÜberCharge beam, so it may be better for you to be in the front to draw those attacks and protect your patients."
"Me? Protect them?"
"Yes. You're both invulnerable, so don't worry too much. As that's effectively the case, your teammates can use you and your patient as moving shields and distractions. But as awesome as it may seem, avoid opposing ÜberCharged pairs; it'd be a waste of the charge. You can also use the charge to save yourself even without any allies nearby. And call for a Medic yourself to alert others of your location. For Kritzkrieg ÜberCharges, charging a Soldier works best thanks to their rockets and Heavies too thanks to their bullets. Remember to watch your back though as you're not invulnerable. For Quick-Fix ÜberCharges, sustaining more than one teammate is okay." Jothicu paused and took a deep breath. "Whew, that was long. And yes, I am done."
"Finally!", Chronicle gave a sight of exasperated relief as the pods opened and the two ponies—not in 'mercenary' gear—stepped out. However, they were a bit uneasy on their footing, though Chronicle recovered quickly and Fluttershy resorted to hovering.
"I'll give you a few sheets on Medic strategy later. Okay, Fluttershy?"
"Okay.", the pegasus answered.
"Now. Let's test out our ÜberCharge power."
"Let's gear up.", said Chronicle and Fluttershy tapped their cards and they were in their Heavy and Medic gear.
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A door bearing the red cross opened and the two ponies—accompanied with another EqU Medic in the colors of Nurse Redheart created by the "Copyspawn system"—marched into action. The clone was equipped with the Quick-Fix while Fluttershy herself had the standard Medi Gun.
Outside was utter chaos. The line was getting pushed further back and nearing its breaking point and the rest were about to retreat. The other EqU Engineer had been 'sent away', both Sentry Guns were destroyed, Applejack was low on metal to make another, and Derpy was critically injured and was hiding behind cover further back from the line. Rainbow had since fallen from the window and was crawling on the ground, too injured to fly. Spike was running frantically towards the line.
"Medic!", he cried out before being slammed by several rockets, sending him landing face-first on the ground in front of Fluttershy, who gasped in shock.
"You know what to do.", Chronicle told her.
She nodded, flipped a switch on the Medi Gun, and a yellow healing beam that bubbled crosses of the Medic and butterflies of her cutie mark was fired. This beam made its way to Spike, who was quickly and completely healed. He got up, he said, "Thanks, Fluttershy!" before heading back to the battlefield. Meanwhile, the other EqU Medic healed up Derpy, who gave a word of thanks before getting back into the battlefield as well.
Fluttershy then turned to Rainbow Dash and aimed her Medi Gun at her, only to realize that the beam was on Chronicle after Spike left the beam's range. The blue unicorn noticed this and moved toward a red truck further into the battlefield, breaking himself from the beam so that it would make its way to the cyan pegasus. Rainbow was up in a second and she leapt to her feet, hovering in the air for a second.
"Yeah, thanks, Fluttershy!", she said before taking off. "Woohoohoo!" She flew up to a BLU Soldier and whacked him with her bat. "Aww yeah!"
Just then, coming over the crest of the hill was a massive horde of BLU Soldiers, a larger one than was previously held off. And not only did they have all sorts of weapons, they had all kinds of headgear, and not just helmets.
"Aww, hay no!", gasped Pinkie.
"This isn't good.", said Twilight.
"I'm not sure we can hold against this.", said Applejack.
"Don't worry, girls!", voiced out Chronicle as he stepped out with the two Medics behind him. "I can handle that. We now have the ÜberCharge."
"Chronicle!", called out Fluttershy. "Are you sure about this?"
"Only one way to find out." He gave one more look at the Soldiers, who were being futilely held off by the others. "Hit it! Both of you!"
Both Medics flipped another switch in their Medi Guns and their backpacks started humming with power. Both of them then fired their healing beams at Chronicle, whose eyes popped open from the boost of power brimming in his body. "EYAAAAAAAAAH!", he cried out as a blue coat of energy enveloped him and turned his eyes white. "HA HA!" A similar coat, but yellow, enveloped Fluttershy, who was too focused on healing to notice the change. Only the other EqU Medic retained her appearance. The three marched forward, the EqU Medic clone using the other two as cover as the BLU Soldiers' rockets barraged Chronicle, who shrugged them all off thanks to the ÜberCharges. 
This taste of power got him laughing like crazy, catching the attention of the other EqU members in bewilderment. "I'm invincible!"
"What in blazes…", gasped Applejack.
"Holy guacamole!", gasped Spike.
"That is so awesome!", squeed Rainbow.
"Whoa!", gasped Twilight.
Pinkie just drew a long breath while Derpy glimpsed the ÜberCharged Chronicle with her other eye.
Via the "Copyspawn system", Tasic communicated through the EqU Medic clone and said, "Girls! Spike! Chronicle's still just one pony. Help us out!"
Immediately, the remaining six EqUs charged as well, staying with the ÜberCharged pair as cover while they all mowed down BLU Soldier after BLU Soldier as they fell over dead in rapid succession. Eventually, the nine EqU mercs reached the BLU checkpoint just before the ÜberCharges ran out, claiming victory.
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After the victory, EqU continued to rest at the building, where Jothicu began working on giving the others what was needed for the ÜberCharge to work on them, starting with Derpy Hooves and Pinkie Pie. The rest loafed around as they (save for Fluttershy and Chronicle) waited for their turn. Applejack was reading an instruction manual, Rarity was brushing her mane while taking with Thenam, Rainbow Dash was napping on a gurney, Fluttershy was reading a few sheets Jothicu gave her, Spike was licking his gem-on-a-stick, Twilight Sparkle was reading a reference guide of some kind, and Chronicle was speaking with Tasic.
"That looks good. Very nice there. Yes!", said Jothicu as he finished the application.
"Thanks a lot, Doc!", said Pinkie as her pod opened.
"Thanks, Doctor.", said Derpy as her pod did the same.
The two ponies stepped out—well, Pinkie hopped out—and they waved to the others. Jothicu then called out, "Spike, Rainbow Dash, you're next."
Rainbow and Spike quickly got up, saying "Finally!" as they made their way to the pods and entered them.
As the pods closed, Thenam suddenly shouted, "Why did I not think of that?! I should add hats and miscellaneous items in the Customizer!"
"Well, I do hope the Spy's got some fashionable accessories.", Rarity said.
"Maybe, but given he's male…"
"I get it. Do not expect too much."
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And that's it for now.
"Really? That seemed to be more Medic strategy than actual story."
Sorry about that. At least I didn't go "cutscene power to the max" since I had another Medic with the Quick-Fix. The secret is that a chip is placed in the mane of the pony. For Spike's case, it will be in his 'pocket'.
"What pocket? The one where he kept his gem when Rarity got ponynapped?"
Yes. See ya on Third!