All Carrot Top wanted was a vacation, but when the Tyrant Sun appears and lays siege to the industrial city of Stalliongrad, the simple carrot farmer finds herself in way over her head. Trapped far from home, with only a few friends beside her, Carrot Top must help marshal the city's defenses and keep the civilians safe--both from the implacable monster outside the walls, and the increasingly unstable chaos within them. Between dwindling supplies, a Discordian anarchist, insane sun cultists, and a city government that refuses to believe the walls could fall, the farmer will have to overcome a host of problems in order that the innocent ponies survive the coming disaster. But overcome them she must, because the coldest city in Equestria will otherwise go up in flames... and will take one million ponies with it.
Lunaverse story, set at the end of the 'Winter' portion of Season 2. Note that RDD has reserved judgement on whether or not this story is canonical.