The Princesses are dead, the elements of harmony perished along with them at the hooves of a Changeling plot. Cadence has taken over, a puppet for the nobility to manipulate, she rings the bells of war and sends Equestria to foreign lands to fight.
One ancient creature sees the death of the Princesses as inevitable, they will always die there no matter what path they take. But the elements of Harmony did not need to. Seeing this as an opportunity to save a world brought to its knees by war simply by changing the elements' lives, he changes their roots in hopes of changing their fate.
(Credit goes to Haylizabeth for lending me her OC Ivy Winter and helping me with the plot! Check out her fantabulous art over on DA: Right here! She's really good.