Well, you know how in the first episode of season 3, Celestia has the ability to use dark magic like Sombra?  
I imagined her getting corrupted by it :3
 
I keep having ideas for a MLP comic but I struggle to draw ponies =w=  
So if anyone wants to use my ideas, feel free but a little bit of credit would be nice ^^
 
Since Celestia had, up until the events of MLP:FiM, been the single ruler of Equestria, she is struggling to adapt. All her loyal subjects now share their love between the four princesses instead of just her. Deciding she has had enough, she uses the strongest magic she can possibly use- Dark Magic. However, it corrupts her and many of the ponies throughout the land. She starts fighting with the other three alicorn princesses, until all of them are exhausted. The four of them disagree on the next course of action, leading to Celestia declaring war on the others. The citizens of Equestria are divided, being forced to choose a side.  
Ponyville’s residents follow Twilight. Many unicorns are also on her side, believing that unicorns are supreme and hoping they will all ascend to alicorn status. Twilight takes Ponyville’s library to be her base of operations, creating a magical barrier around the town. She hopes that Equestria can returned to being led by all four princesses.  
Many loyalists follow Celestia, believing her to be the one and only Princess. The Canterlot guards also stay with her. She stays in Canterlot’s Palace, capturing those who have not chosen to stay by her side. They are kept in the Canterlot caves. She is strict and harsh, but those around her have become increasingly corrupted. She wants to rule alone.  
Luna’s personal guard protect her in the Everfree Forest. Those who think that the two original Alicorn princesses should rule are her followers. She lives above an Ursa Cave, where an Ursa Major and Minor sleep. As they are constellations, Luna has control over them.  
Cadence stays at the Crystal Empire. It is a safe haven for those who have not decided on what side they wish to take. Cadence thinks that each princess should rule a certain part of Equestria. Those who agree are allowed to live closer to the palace. Her and Twilight are still on good terms and offer help during times of crisis.