Before the wedding could actually start, both Venus and Shining Armor were very busy greeting all the guests that had been invited. On Shining's side there was his family and friends (most of whom were guards), while on Venus' side were Cadance's family (who had decided to treat the avatars as their own children), and a big mix of ponies and others from all around, mostly from the crystal empire and the city of Belemoor (most of those were also guards, of course).
"Uufff... Weddings are hard work." Shining Armor commented after a particularly grueling session of greetings "And the fact that we're probably going to have a changeling attack doesn't help."
"But isn't that exciting?" Venus asked him "The day we confirm our bonds with each other is also the day where we might deal a decisive blow to the changelings." She then nuzzled him "Besides, delaying our wedding would just give them more chances to cause trouble, and I know that you wouldn't stand for that."
Shining Armor smiled and nodded "Yeah, but I'm still going to worry." He then looked at Rarity "Any news about the princesses?"
Said unicorn closed her eyes and cast a spell, receiving a reply after a few moments.
"Looks like this is going forward after all." Rarity said with a wry smile "Apparently the shards of chaos formed a Congregation of Chaos and the princesses have to contain it for now." She shook her head "Because of course they would find the most inconvenient time to do that."
Applejack, who was beside her, rolled her eyes "And we're going to have to dealt with that after this mission. Of course."
Rarity then closed her eyes again, apparently receiving another message. After a few moments, she spoke.
"A tendril managed to escape the Congregation." She opened her eyes "The Crusaders and Spike were sent after it. Want to bet that it's going to come straight here?"
"No bet." Applejack replied, before closing her eyes and opening them again, this time seeing through a great distance. It took only a few moments for her thoughts to be confirmed.
"Hey, Fluttershy." She muttered seemingly to herself "Tendril of Chaos coming, ETA is three minutes." And she sent an image of what she had seen via her empathic connection with Fluttershy.
Said pegasus received it and proceeded to pass it along to the other Knights present in the city. That was a demonstration of how much she had grown. Previously, even with the connection of a feather as a medium, she wouldn't have been able to do so much, but now Fluttershy was capable of all that and so much more.
Pinkie and Twilight, who had received the message as well, passed the word along to the guards via their multiple bodies, and said guards proceeded to initiate the appropriate counter-measures, which were mostly based upon herding the civillians (who already knew something like that was probably going to happen) to the most heavily protected areas. Further steps would be taken once more details were known.
Rainbow Dash flew Fluttershy to a better scouting position, and soon after both of them could see the approaching Tendril. It looked somewhat like a comet, with a sphere in the center and a flaming tail dragging behind it. However, the sphere was spinning at high speed like a drill, and the flames of the tail were actually green, and their movement made them seen almost solid instead of simply being fire.
Fluttershy took the time to remember what Twilight had taught her about such things. Congregations of Chaos were what happened when an extreme amount of shards of chaos joined together, resulting in an existence that went backwards and actually obtained inteligence. When one of them appeared, it meant that Discord rebirth was nearing.
Meanwhile, a Tendril of Chaos was a shed off piece of a Congregation, designed for an specific purpose. It acted like a smart spell, and whatever form it took greatly surpassed the threat level of ordinary chaotic events created by shards.
At that point, it couldn't be denied that the Tendril was going straight towards the city, and with Applejack and Fluttershy's combined senses, it didn't take long to decide that it would take an unreasonable amount of effort to intercept it. There was a brief discussion between the Knights via Fluttershy's empathy, in which they decided to allow it to hit, while keeping track of the possible impact sites, just to make sure.
A few seconds later, both Fluttershy and Rainbow Dash saw that something was following the Tendril. It was Spike and the Crusaders, with the dragon having turned into a massive flying form, and the fillies using their power to provide extra propulsion. The result looked like a dragon wearing a jetpack.
"So... Awesome..." Rainbow Dash muttered before regaining her focus.
The rest of the Knights were informed of that new development (though they already knew that the four would come) and the last few preparations for impact were done by both the Knights and the guards.
The Tendril crashed right in the middle of the city, the impact not causing any physical damage but releasing a pulse of chaos magic that scrambled all of the automatic magical defenses, causing them to go haywire and disperse random effects throughout the entire city, forcing the guards to fight back.
And that wasn't the last of it. As if the crash was a signal, hundreds of changelings suddenly burrowed out from the ground a distance away from the city and charged towards it.
Every single one of those changelings was wearing an Artefact Armor. All of them shared a common theme of "modularity", seeming like they were designed to fit with each other, but they were different enough that it became clear that each changeling had built their own armor.
Chrysalis had obviously made good use of the techniques that had been spread around by the shard of chaos.
All those things happened within seconds of each other, but neither the Knights nor the guards were taken off-balance by them. A series of rapid fire messages passed through Fluttershy's Empathy Network as the defence force scrambled to respond.
'Falling back to the city limits.' That was Fluttershy.
'We'll give support to the guards and watch out for ambushes.' Rainbow Dash.
'I'm coming towards bride and groom to initiate protection plan Chaos Realm.' Sunset Shimmer.
'I'll give support to Sunset.' Rarity.
'I'll take over the Command role. Rarity should assist me when she is done.' Trixie.
'Copy that.' Rarity again.
'Me and Pinkie are going to isolate the effects of the Tendril.' Twilight.
'The defences will be up and running again before you know it!' Pinkie.
'Ah'm gonna keep watch on the critical areas for any more surprises.' Applejack, doing the neat trick of making her accent come across via empathic communication.
Their roles were decided quickly and easily, since they had made plans upon plans to be able to react to all sorts of eventualities, so the only thing needed was executing them. Before ten seconds had passed, all of them had already started:
Sunset teleported close to the impact site of the Tendril, before setting upon it with a veritable bombardment of sealing-type spells. Rarity accompanied bride and groom in a frantic gallop towards Sunset, keeping aware of any possible ambushes, her swords drawn and ready.
Applejack focused her powers with a chant of 'Myriad Truths...', expanding and focusing her sight. Pinkie Pie and Twilight slammed their dozens of forehooves (from all the clones) into the ground at the same time, channeling magic through the defense systems to fight chaos with chaos.
Fluttershy and Rainbow Dash flew back to their chosen battlefield, the former doing her scouting role to the utmost, while the latter was focused on keeping both of them safe.
Quickly enough, the changelings got ever closer to the limits of the city, when they started to jump into each other, their armors merging seamlessly to allow them to form animal constructs, each of them composed of more than a dozen changelings. In their previous appearance, such a thing was reserved to only a few elite groups, but the armors seemed to make it easier. There were scorpions skittering through the ground, wasps diving forward, ants crushing everything they passed...
However, before they could enter the city, the first wave of guards rushed out to meet them. And every one of the pony guards was also wearing Artefact Armor.
One of the first jobs Coco and Suri had received was to refine their basic artefact forging method in order to create a standard procedure for the Equestrian Guards to create their own artefact armors, which would be designed to have synergy with each other and the normal tactics of the Guard.
The enemies had enpowered themselves... but the Equestrian defenders would not be left behind.
The two forces clashed, heavy armored earth ponies breaking the charge of the big enemies while lightly armored pegasi flew through the air in weather manipulating formations and magically enhanced unicorns alternated between covering fire with spells and protective barriers.
More and more reinforcements from both sides kept showing up, increasing the scale of the battle successively. The changelings were known for their horde tactics, but even they were hardpressed to outnumber the contingent of guards, which seemed to consist of about 90% of the ponies in the city, many of whom had lay in wait for the time of battle.
Fluttershy and Rainbow swooped down to support the guards, keeping most of their strength in reserve to deal with any eventualities. Fluttershy was also keeping careful track with her empathic senses, so when groups of changelings started disguising themselves as guards to try and infiltrate their enemy, she led Rainbow Dash into quick strikes to deal with those.
And yet, that wasn't the biggest reason why she was doing that, Fluttershy was actually waiting for a very particular changeling to appear. And soon enough...
'Chrysalis has infiltrated the city.' She sent the message 'I can't figure out her exact position, but she's here.'
Upon hearing that, two of the Knights reacted in very particular ways. Rarity tensed up, knowing that her duty would be to delay Chrysalis if she came after Venus before the Chaos Realm operation was complete. Meanwhile, Trixie used a spell to send a message to a very particular duo of ponies, who were waiting at a very particular location.
They were Moondancer and Minuette, and they were inside a small open space located almost three miles under the ground.
"The time has come." Minuette said, upon receiving the message.
"Let's do this!" Moondancer declared with a grin.
Together, they called "Magic Ritual: Ultimate Prison!" As they activated a gigantic ritual circle, which was located too far underground to be affected by the chaos.
The result was a sight to behold. A gigantic sphere of energy appeared around the city, a shield spell so powerful that not even Shining Armor's strongest barriers could compare. It didn't only enclose the city, but in fact an entire zone that was three times the diameter of it. That was to catch even the stragglers and rear guard of the changelings inside and prevent their escape.
That operation wasn't just about protecting a wedding, but about dealing a blow to Chrysalis' forces that they wouldn't be able to recover from.