My Little Pony: Friendship is Magic final season finale

Chrysalis comes back to take over Equestria, but she can't do it alone even though she has minions.
She needs somepony else, so she brings back the horrible Sombra and the great powerful Tirek, and he gets to feeling that evilness that once took over Princess Luna.
So they gathers that evil spirit and puts a super dark spell on it, and makes it in a form of a drink.
So Chrysalis can take the form of a pony at random that Luna has possible never seen before and surprisingly she hasn't, so it all goes according to plan. What they do next is try to convince Discord into being evil it takes many tries but they finally convince him, or so they think.
For the poisoning Luna has drink, it doesn't turn her into Nightmare Moon the second she drinks it, it makes her super negative towards her sister.
She soon gets in a fight with her, then she becomes Nightmare Moon.