Unfinished story concept: The Harbingers in Ponyville

I think I wrote this while going for the achievements in The Binding of Isaac. I decided to read up on some of the imagery in the game and the stories from which it was derived. That led to this.

Rated T for violence.

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The Harbingers in Ponyville

When the Harbingers came to ponyville, Celestia collected all of the other Alicorns, as they were the only ponies meant to survive.
Then Twilight asks her what is going on, as they watch the attack through a viewing window (courtesy of Netflix), and Celestia begins to explain, but shortly afterward, her voice cracks and she breaks down completely, as Luna moves to comfort her.  Twilight asks why they aren't doing anything to stop this, and Luna explains that they are not meant to interfere.  Twilight refuses to accept this, and Cadence follows suit, not wanting to lose Shining Armor.  Sadly, all they can do is watch, no matter how hard they try to escape the alicorn realm, they find themselves unable to do so.
So as Twilight and Cadence become increasingly frantic, the rest of the mane six, and perhaps Shining Armor attempt to get the other ponies out of harm's way, with mixed results.  They wonder where Twilight is, but are forced to focus their attention on staying alive.  Pestilence declares that it is his day to take over their "miserable world", and essentially monologs until somepony interrupts him.  He then rushes over, proclaiming that the offending pony will be the first to taste his power, and with a touch of his horn, inflicts some kind of illness.  He then turns to the other three and says "what are you peons waiting for?  ATTACK!"  They do so, though it is clear that they don't particularly like him.
Shining Armor tangles with War, and quickly discovers that the red stallion is an unstoppable juggernaut, constantly looking for any opponent he can find.  Buildings crumple like paper as war runs through them, taking on entire squadrons of royal guards and wonderbolts.  Ponies attempting to hide find themselves at the mercy of Famine, and I haven't quite pinned down what she does yet, only that she is manipulative, though not treacherous to her fellows, and perhaps a pegasus as well.
As Pestilence, War, and Famine rampage on, Death moves in, seemingly for the kill.  It is implied that Death kills anyone who is downed by the other three.  Then at one point, one of the mane six, probably Rainbow Dash, rushes toward one of the Harbingers, only to stop short as she comes within inches of slicing her own throat on Death's outstretched scythe.  A second after she stops, a large chunk of rubble falls on the spot where she would have been had Death not stopped her.  Death retracts his scythe and moves away as Dash realizes what almost happened.  One of the other ponies pulls Dash away from the area, and they continue battling.  It isn't until Death blatantly protects a pony from injury that the five friends realize that Death is going out of his way to prevent loss of life, while making it look like he is aiding his comrades.
Meanwhile in the Alicorn realm, Twilight and Cadance have been watching intently, and one of them remarks angrily about Pestilence’s cruelty.  Upon hearing the name, Luna asks who Pestilence is, as she and Celestia had been told of the Harbingers long ago, and Pestilence was not among those foretold.  Celestia explains that the Alicorns exist to counterbalance the existence of the Harbingers, and each of them serves as a counterpart to one of them.  Celestia is meant to be a counterpart to their leader, but she knows for a fact that Pestilence is not meant to fill that role.
At that moment, Twilight hears a voice in her head; the voice of Death, who has otherwise remained silent.  He sends her a cryptic message, which she then repeats aloud.  Celestia and Luna immediately realize that her harbinger has spoken to her, and the four attempt to puzzle out what the message means.  Ultimately, they decipher the message, which instructs them to work together and perform a spell simultaneously.  Arranged in a circle, the four touch the tips of their horns, and activate their magic.
Meanwhile in the mortal world, Pestilence, War, and Famine continue to wreak havoc and terrorize the ponies.  One of the mane five, or Shining Armor, blindsides Pestilence, and he angrily turns to retaliate, only for Death to block the attack with his scythe.  Enraged at the perceived treachery of one of his subordinates, Pestilence rounds on Death attempting to gore the other harbinger on his horn.  War and Famine cease their own activity at this and turn to watch in confusion; for two harbingers to fight each other is inconceivable to them.
Ultimately, Pestilence overpowers Death, but before he can deliver the finishing blow, a LIVID voice calls out his name (think Frank Welker's voice for the Megatron from Transformers Prime).  Shaking in terror, Pestilence turns to face the source of the voice as a white alicorn flies in and lands, his hooves connecting hard with the ground.  As Pestilence begins groveling, the alicorn angrily beats him to within an inch of his life, while the other two help Death back to his hooves.  The alicorn then orders the others to fall back, and begins dragging pestilence behind him.
One of the mane six approaches the alicorn and begins to thank him for his help, but she is quickly swatted aside.  "Insolent worm!  You dare speak to Conquest?!"  he then turns to address everypony in the area.  "It is not yet our time to act, but we shall return, and I will crush ALL of you pathetic insects beneath my hoof!  For now, my subordinate requires discipline."  and with that, they depart.  The princesses enter the scene as the harbingers depart into the horizon.  While Cadance and Shining Armor share a tearful reunion, Celestia and Luna perform crowd control. Twilight reunites with her friends, and as they share a group hug, she once again looks toward the departing harbingers and her eyes lock on Death.  He briefly turns back to look at her as well.  the implication being that she thanked him for his help, and he did the same to her.

Notes:

• Pestilence would have the same voice as Transformers Prime Starscream
• Conquest has the voice of Megatron from the same series
• War is essentially a pony equivalent of Marvel’s Juggernaut
• Famine’s body appears shriveled and mummified
• Death is the gentle one, and never speaks.