[The day after the Necromancers attack.]
The sergeant runs into the war tent "No mam, nobody has seen your friend Fluttershy since before the attack." Twilight sighs, face-hoofing as she says "She was with us after the necromancer fled, so she wasn't kidnapped. She's got animal friends so she should be ok."
Luna looks at the remaining elements "We will start making plans to follow up the leads, hopefully Fluttershy will send us word, but we can't risk her going undetected, we need to find them." Luna looks at each pony in the tent, and the way she speaks hint of her days as Equastia's war leader "I heard 3 possible investigations we can begin immediately.
-The first, and most important to explore is the desecration of Pegasi grave sites. It sounds like her wings don't last forever, so if we investigate we can see if thier is a pattern to it.
-Second, Fluttershy talk to animals, we need to get some experts in here to try and follow the animals she talked to, with luck one of them knows where she went.
-Finally, Rarity has generously pointed us to Valley's Armour manufacturer, I suspect it's well concealed, but their has to be a connection, we will find it."
The elements can help me plan these missions. Sister, we interrupted your explanation, go finish while we do this." Celestia nods and leads Twilight back into the side tent.
"As I was saying not even five years later we were at war with one another, my other students fighting against her, their once friend. Yes at the time I had multiple student's, a mistake to be sure, one at a time is enough. She desecrated thousands of graveyards, and all sorts of undead flocked to her banner." Twilight give Celestia a look, and she pauses "I know about the undead, but I've never heard of somepony who can control them, I know it sounds bad, but why did you go to war, as gross as it sounds, it appears the undead are just her elaborate levitation spells."
Celestia pauses, and laughs "Oh dear, that does make a sort of twisted sense, but Twilight you must understand, their is such a thing as evil in this world, you've witnessed it first hand. The real problem with Serene's magic isn't that she has control over the dead, though that does make it hard to support someone, it's that her powers are powered from this darkness. You remember Nightmare moon and Sombra? Both of them used power from this same wellspring, just using it twisted their minds and body's. My sister Luna is a wonderful pony, I love her dearly, but even you saw what that dark magic did to her."
Twilight smiles "Of course, and until recently you haven't had access to the elements of harmony, so you couldn't attempt to use them. That solves it, we will use them on her, and purge the darkness from her." she sees the sour look on Celestia's face "It is true that I was unable to use them, but before the war I did try a ritual on her, in fact it's the same ritual I used to help you ascend to an Alicorn, in theory on her it should have let me change her talent, but instead it almost killed her, one of the largest reasons she fled."
Pausing Celestia looks at the other tent, where the shadows of Twilights other friends and Luna dance, as they plan and scheme. "I thought her dead, at the end of the war, her last living friend escaped to tell of the horrors that lurked under her control, I cast one of my most powerful offensive spells at her castle, and melted it to prevent their escape, I don't know how she escaped, even Luna would have died in that inferno."
Twilight shakes her head "Cutie mark in death magic right, probably related, in a few years I could probably develop a spell for it. I'd like to know something else, why the communications blackout? it was strange to say the least." Celestia looks at Twilight with sorrowful eyes "I had to be sure you were, well... still pure, later in the war... well miss Valley started fighting me with my own people, twisting my words and corrupting people close to me. Only half the army's my own fought against were undead, the others were living, ponies that had risen up to overthrow the 'dictator' that ruled Equestia. It was only through luck and ingenuity that we manage not to kill any of them."
Pausing she adds "Twilight, while you can tell the others anything you want, don't tell them this... assuming the worst, that Fluttershy has been captured, their is a very good chance that she's being tortured. During the last quarter of the war, as we were winning, every pony we captured from her dungeons was tortured... I mentioned her last living friend? that friend died right after from a broken heart, and blood filled lungs."