The Vampire Diaries introduced viewers to the Long Island Iced Tea of curse-breaking spells last night.

But instead of a mixture of ingredients that simply lead to a hangover, the recipe Katherine described to Elena could result in the sacrifice of us of almost every Mystic Falls resident we know and love. Welcome to the latest twist in the most shocking show on television.

Before I get into the heart of my "Katerina" review, let's recognize the work of Nina Dobrev.

Within the course of one hour, this actress portrayed Katherine as a human being in Bulgaria; Katherine as a pretend English woman in Great Britian; Katherine as a weakened vampire in present day; and a couple versions of Elena, one confident, the later one a tear-filled mess. That's gotta be some kind of record for a star of a show.

Overall, "Katerina" was a necessary installment, an essential information dump that left me furiously scrawling notes and trying to keep up.

It certainly wasn't the most action-packed episode in series history, as my one complaint would be that the mythology was mostly revealed in an expository manner. Really, we all just watched as Katherine sat there and spilled everything to Elena. But there was a whole lot to spill, and it left me with a number of points/questions. To wit:

Now we know why Elijah thought the Petrova bloodline stopped with Katherine: because her parents gave her daughter away. There could be any number of flashback episodes that take us through Elena's more immediate family history, as I'm left wondering: did her relatives also resemble Katherine? How many other dopplegangers are out there or have been out there?

The dopplegangers were created as a means to undo the sun and moon spell. But who created them? Because Slater - who I adored... a nerdy vampire, how funny/awesome was that?!? - said the goal is for vampires to break the curse before werewolves do, I'm hoping we receive more background on the feud between these creatures.

In case anyone missed it, the ingredients Katherine returned to Mystic Falls to collect are: a vampire, a werewolf, a witch, a doppleganger and the moonstone. No word yet on whether or not a partridge in a pear tree is also required.

Before the episode concluded, I turned to my wife and said there's always a last-minute twist. I thought I was proven correct when Elijah was revealed to be compelling Slater... but there was a twist on the twist. Dr. Jonas Martin is working with this Original. Do we also think Luka is in on it? Or being used as a pawn by his apparently evil father?

One problem with how Katherine simply listed her history, along with the basis for her return, is that we're left to ponder a major question: is she telling the truth? When she was first locked in the tomb, she wailed about needing to protect Elena - but we have to assume that was a lie now, right?

It will start to feel annoying and manipulative if Katherine's story changes from week-to-week. I have to believe we're getting accurate information this time, especially because it doesn't paint Katherine in a flattering light. Why make up that she wants to help Klaus sacrifice all these people?

As Katherine suggested, this all seems to be leading toward a major decision for Elena. There is one way in which she can save those around her: by taking the same action Katherine took over 500 years ago. By becoming a vampire.

Finally, speaking of Klaus, one final question before I turn this review over to reader responses: considering how greatly they've built him up - Elijah is the "Easter Bunny" compared to this Original, Damon's latest lucky lover said - who will they possibly get to portray this ultimate villain? If they show is searching for an intimidating, angry, scary actor, only one name comes to mind:

Mel Gibson. What do you think?

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.