Here, Velvet is sporting a new sparkly black dress that Rarity just developed for the holidays. The key feature on it is the low cut collar, which helps to accentuate and emphasize neck fluff, such as that on a reindeer (or a kirin, griffon, etc). They're on a mountain overlook by some fancy reindeer's cabin, probably celebrating a Hearthswarming Eve near Velvet's hometown of Reine. How did Rarity get to Reine? Probably through a portal mirror would be my best guess.
More to come soon, probably later today. Stay tuned and keep it classy, ponefriends!