A Reaper dreadnaught confronts Celestia, intent upon indoctrinating the leadership of the ponies. Said Reaper quickly learns exactly why Celestia has earned the title Unconquered.
There are things a Princess cannot do. Over the centuries, Celestia has been asked to do those things countless times. And the moments when her ponies need her the most are the ones where she can't do anything.
Only a few hours after the Griffon Empire declared war on Equestria, Princess Celestia waved a white flag and asked for an audience with the Griffon Emperor. The Emperor thinks she's here to negotiate Equestria's surrender. He's wrong.
For nearly every citizen of Equestria, it's a holiday: a chance to get together with friends, gather a few treats, and laugh in defiance of the darkness. For Celestia, Nightmare Night is something else entirely.