spoiler The Rainbow of Darkness from Rescue at Midnight Castle shows up in FIM

[Singe 2,111]

So lets say the writers decide to reach back to the old MLP series to bring back The Rainbow of Darkness that Tirek used in Rescue at Midnight Castle. The Rainbow of Darkness changed the ponies into dragon monsters in that movie.

Now instead for FIM the Rainbow of Darkness corrupts a character and turns them into a monster or evil counterpart.

Princess Luna to Nightmare Moon.

Princess Celestia to Daybreaker

Who would be some characters that would be the best targets to change with the Rainbow of Darkness and what should it do to that character?

[Goat-kun 2,530]

Luna? Celestia? Lunestia! All shall be one beneath the old light of harmony.