Undead Raiser

The harmony that kept Equestria serene and untainted was brought to a very abrupt end by an accident. A horrible accident that was brought by a good intention.

A secret group of seven ponies, self proclaimed as the Holy Pillar, traveled across the land to find the most rare and yet despicable book of Dark Magic, including an infamous one featuring a very horrific type of necromancy called Helknut. They made the right choice to take it far away from prying eyes and burn it along with the other books through their magic. That looked easy.

But that good act backfired at them as the books' magic was released and fused itself with the dark magic of the other books and the book's ashes altogether. That fusion unleashed a pestilent aura that engulfed a huge part of the land, turning the ponies in the area into seemingly mindless, undead creatures. In other words, you guessed, zombies.

The plague was eventually named as Necromyth. The plague spread rapidly in the ark of three days due to the infected ponies continuing it's job. Higher places like Canterlot were untouched... At least for now.

Unlike most of the paranoid stories about zombies, this plague turns it's victims into not one, but three different type of zombies, depending of the circumstances. The most common ones, the Lessers, are the typical blind, mindless flesh eaters, except that they were slightly faster and can rely on predatory instincts. They tended to revel than their victim's flesh tasted like that of their own former foods.

They looked bad enough, until the Flailers showed up. And then they were eventually followed by the lethal ones, being the third type. They were an rare example, being a result born by a medic's attempt to create a vaccine against the plague that went horribly wrong. They were sentient and dangerous and only the luckiest ponies lived to tell the horrible story.

As somepony can guess, everything below Canterlot and others had gone downhill, with any type of chaos imaginable, and non, devastating the land. Even the Princesses' magic could do nothing against it. Everything was almost doomed from there.

But then someone emerged from this chaos, being something far worse than the Necromyth itself...