WARNING! SPOILERS AHEAD! SPOILERS AHEAD!
So the episode starts off with Twilight learning to fly with Rainbow Dash and failing hilariously. First off, it's nice to see that Twilight still isn't used to her wings yet and can't fly worth a crap yet. Adds something to be brought about as the season continues. She hits the floor and Applejack compliments her calling her "Princess Twilight" and Twilight saying not to call her that. Rarity tells her she should embrace her title as Princess since she already decided not to wear her crown everywhere she went. Good to see that Twilight is still just as modest as she was three seasons ago in Boast Busters. Twilight tells her it's okay for other ponies to call her Princess but she would prefer her friends not to since it wouldn't feel right. She also mentions that she still isn't used to her wings and wonders how she'll preform her "part" (vaguely mentioned and rightly so) in the Summer Sun Celebration two days away. I guess this means that the first three seasons took the time span of about a year or so. Looks like that discussion has been dealt with. So Rainbow Dash tells her to try her "big finish" again and she fails in the way you'd expect, cute and hilariously, cue the intro.
As was assumed after the Season 3 finale, the intro has changed again, but not as much as you would expect. It basically plays out the same as the intro from Season 2 and on with the only difference being when the Mane Six all get together where it (of course) has Twilight with her wings, the other main ponies changed poses and they added Big Mc, Granny Smith, Zecora, Snips, Snails, Mr. and Mrs. Cake, Mayor Mare, Spike and the CMC with Photo Finish taking a picture of them all. The flash is a transition to Spike sending the scroll to Celestia per the usual intro which leads to the other change of adding Luna next to Celestia to look at the new picture alongside her. I was expecting a lot more change but I'm not disappointed by the lack of change. My only comments are that some of the characters, like Snips and Snails for example, seem oddly placed. It might just be me, but I feel the same way about Mr. and Mrs. Cake and even Mayor Mare. Don't get me wrong, I think they have more of a place there than Snips and Snails, but I don't feel that they have as much of a place there as Zecora or the Apple family. It's good to see Spike in the picture though, poor Spike is almost always left out. It's also nice to see Luna getting some well deserved recognition by adding her into the intro.
Back to the episode, the Mane Six stare at the new glass window of Twilight's transformation (I wonder how much they pay the people that make those in the show since they make them so often ) and we get a little more banter of Twilight's modesty and Rarity's swooning over thinking of herself as a Princess. Fluttershy mentions that they won't want to miss their train and Applejack comforts Twilight saying that they may have to separate from Twilight, but the Elements of Harmony keep them connected and "no amount of royal duties is gonna change that".
The five ponies leave with some Pinkie Pie funnies added in, and Spike begins checking off the checklist and mentions they're ahead of schedule suggesting a quick trip to Ponyville for the day leaving the day before the Summer Sun celebration to finish off what's left of the list. Twilight freaks out over this in the same way she always does (see? Meghan was right, Twilight is still the dork we loved prior to her ascension) and decides against it. Celestia comes in and mentions looking forward to the Summer Sun Celebration for the first time because of the yearly reminder of her sister's banishment that it always was to her. I love how they are finally developing Celestia's feelings on the subject of banishing Luna because prior to this, the most we got was in the pilot where it narrated "Reluctantly" and they just kind of left it at that. And while I didn't hate the idea of bronies expanding on the idea (I loved it in most cases), it's still nice that we have some canon to further establish what the fans interpreted and what Lauren's original vision was. Celestia continues by saying that now it serves as a reminder of Luna's return and Celestia's reunion with her. Celestia tells Twilight that she knows what she feels about being away from her friends and will always be there when she needs her and hopes Twilight will be there to do the same. The two share a cute, feels moment and Celestia leaves Twilight and Spike to checking the checklist one last time before bed. As Celestia walks away, a black vine breaks out of the floor and we hear Celestia scream before it cuts to black.
The next morning, Twilight finds that both the sun and the moon are in the sky dividing Equestria's night and day in half across the sky. Twilight goes outside and attempts to calm the ponies of Canterlot before two royal guards lead her into the castle telling her Celestia and Luna are gone. They ask for her orders telling Twilight that because they are the royal guard and take orders from royalty, they take orders from her since Celestia and Luna have vanished and Cadance in overseeing the Crystal Empire (yay, a mention). Twilight tells them to continue searching for the Princesses and report to her when finding anything as a third guard comes in and informs Twilight that the Everfree Forest seems to be invading Ponyville. In Ponyville, the animals have taken shelter in Fluttershy's cottage to escape the same black vines from earlier while the Apple family tries to tear them out of the ground thinking they're weeds. Rainbow Dash, meanwhile, begins to deal with some oddly spiked clouds that attack her with lightning when getting near them. Over at Carousel Boutique, Rarity notices the sky but ignores it until the black vines cause her magic to go on the fritz. Rarity thinks it's Sweetie Belle and the rest of the CMC pulling a prank on her but sees that Sweetie Belle's horn is freaking out as well. Twilight grabs her crown and flies with Spike to Ponyville as the other Mane Six gather at Town Hall and discuss whether they will be able to get rid of it before it takes over all of Equestria. Twilight and Spike crash into the library where the rest of the Mane Six are attempting to find information in a book. Twilight gets them up to date and prepare the Elements saying she thinks she knows whose behind what's going on.
The six summon Discord, who had been taking a shower and singing "Winter Wrap Up" to himself (lol) and tell him to fix what he's done and release Celestia and Luna but swears up and down that everything happening is not his doing and he has no idea what they are talking about. He also mentions that since he's reformed there's no reason that he would do this. They don't believe him and begin to prepare turning him to stone until Fluttershy intervenes and wonders if he is telling the truth convincing the others to instead have Discord help find out what's going on. Discord plays around saying that he doesn't feel up to the task considering all the accusations and redirects the group to Zecora who happened to be walking by with a cart of her stuff. This is something else that I'd like to address and that is reformed Discord. I give major props to Meghan McCarthy for being able to keep Discord as the lovable asshole he first saw him as and still not have him as the antagonist as was established in the last season.
The six go to Zecora and hear that the vines have driven her out of her home. She also doesn't know what is going on but gives them a purple colored potion that she herself cannot use, because of it only responding to Alicorn magic, and may tell what is going on so long as Twilight turned it white then drank it. Twilight does so and her eyes turn bright and she is teleported into the past and witnesses Luna's transformation into Nightmare Moon at the ancient castle from Friendship is Magic Part 2 and Celestia banishing her to the moon. Part 1 ends with her transformation and Part 2 begins with her trying to kill Celestia before being banished into the moon by Celestia and the Elements.
I can easily say that this is my favorite part of the premiere. It registers so many feelings from me be it me shaking with excitement as Luna loses her temper and transforms to me choking up when Celestia begins to cry before using the Elements. It is done so well and has been one of my favorite scenes since Chrysalis's reveal in Part 2 of A Canterlot Wedding. My only gripe, and a small one at that, is that after Luna transforms and Celestia calls her Luna, she denies the name calling herself Nightmare Moon and it's done in a bit of a lame way. But compared to everything else that happens in this scene, it's a very, very small problem.
Twilight returns from the past and tells everypony what happened but is still unable to explain what is happening to Ponyville. Zecora suggests another sip of the potion and Twilight obliges. Drinking it takes her back to when Celestia and Luna turn Discord to stone. Twilight is then teleported to another part of the past where she sees Celestia and Luna get the Elements from the Tree of Harmony. In the flashback, Celestia mentions that the Tree of Harmony will still be powerful enough to contain whatever grows there even without the Elements.
The flashback ends and Twilight tells them about the Tree of Harmony and leads them into the Everfree Forest to save it. Along the way they come across a brand new creature called a Cragidile, a crocodile made of rocks (and it's the best original creature since the Timberwolves and isn't made using CGI -squee!-) which almost eats Twilight. Once they trap the Cragidile, Applejack and the others decide that they may be better off going to find the Tree of Harmony without Twilight due to her being the only Princess for Canterlot and Ponyville and the uncertainty of finding the Princesses even if they succeeded in saving the Tree of Harmony. Twilight begrudgingly agrees and leaves the Everfree Forest with Spike. They come across Discord and Twilight tells him what happened and why she is no longer with everypony else and he baits Twilight into going back by saying that staying behind is the equivalent of thinking she is better than everypony else.
Meanwhile, the others find the Tree of Harmony but are unable to stop the vines from progressing onto the Tree. Twilight and Spike continue going through the forest and Spike climbs a tree and sees the others nearby. When going to tell Twilight, he sees her being attacked by gas spraying vines and get the Mane Six to save her just before taking her away. The six go back to the Tree but Twilight is unable to get close to it without getting caught in the vines. Twilight then remembers what Celestia said in the flashback about the Tree still being powerful without the Elements and figures out that giving the Elements back will save the Tree and rid Ponyville of the vines. The others are unsure of the idea because of the threat Discord would pose without the Elements and because of the Elements being the thing that connected them all. Twilight tells them the Elements may have brought them together, but friendship is what keeps them together regardless of the Elements. She also mentions that being Princess may give her new responsibilities and test their friendships, but it will never break it.
With that, the six allow Twilight to take the Elements out of the crowns and the necklaces and put them into the tree. Doing so destroys the vines across the Everfree Forest and Ponyville as well as frees Celestia and Luna from their vine prisons next to the tree. The three Princesses reunite when Twilight's eyes sparkle again as they did in the Season 3 finale and the tree grows a bud out of its roots. Twilight opens the bud revealing a box with six locks on it and asks Celestia what's in it. Celestia doesn't know but tells Twilight she won't find it alone referencing the rest of the six. When out of the Everfree Forest, Discord congratulates them but happily notices the Elements are gone. But Fluttershy tells him that the six are still friends and that if he wants to stay friends (most likely with Fluttershy herself specifically) he won't do anything wrong and help clean up instead to which Discord agrees.
They continue walking home and Applejack asks why everything didn't happen earlier and Discord mentions that he doesn't know because his seeds should have sprouted ages ago. Twilight begins to question him but Discord instead gives her more of the potion from earlier taking Twilight back to when Discord was being turned to stone. The flashback remains the same but focuses on a bag of seeds Discord was throwing while talking to Celestia and Luna after being told about the Elements. It turns out that those seeds were called Plunderseeds and should have stolen the magic from the Tree of Harmony and captured Celestia and Luna all those years ago but where stopped by the Tree of Harmony because it still had the magic to do so until that moment. Twilight asks him why he didn't tell them that earlier and he says that he didn't because he, as a friend, wanted to teach Twilight a lesson about being Princess. Time passes and the day of the Summer Sun Celebration begins. Twilight's crown is replaced with another and Celestia tells Canterlot how the Summer Sun Celebration is now a celebration of Luna's return. Luna lowers the moon while Celestia raises the sun and when it's at it's peak, Twilight flies into the air and fires magic shaped as her cutie mark into the sky presenting her part in the celebration so ending the Season 4 Premiere of My Little Pony: Friendship is Magic.
I will begin by saying that this premiere was incredibly satisfactory to me and left me with a lot of great questions that I know will be answered as the season goes on. Obviously, the first thing to address is the new story arc that will encompass all of Season 4 and will probably be mentioned multiple times in the season. And after reading Meghan McCarthy's tweet from her live tweet session during the episode, she's revealed that this is what she meant when they said they were doing something that they had never done before in any MLP generation. Never before has MLP had a season wide story arc and it will be interesting to see how it is dealt with. And for the record, I don't really count the Grand Galloping Gala episodes from Season 1 as a season wide story arc. The reason why is because, if you think about it, there was only three episodes, the first episode established the Gala (The Ticket Master), the second episode expands on their preparation for the Gala (Suited for Success), and the third episode is the Gala (The Best Night Ever). I think it would need more episodes between the first and last to be considered a season wide story arc especially if the season consists of 26 episodes. Whereas in Season 4, they will have at least 5 episodes between the beginning and end of the arc. They could even double that if they had a two-parter mid season but I honestly don't expect that from them. They could also have the episode right before the season finale lead into the season finale that reveals what's in the box. I don't know how they are going to go about this new development to MLP, but I'm very interested and eager to see how it unfolds.
Another thing I wanted to address was Discord. It's pretty obvious at this point that Discord is going to have an episode, at least if you got the spoiler that he has a song this season. I'm curious what the episode will be about since he is technically free to take over again since the Elements are no longer in the Mane Six's possession. The song may even be about him fighting against himself whether he should take over again and make everything as chaotic as he would like it or whether he should keep his friendship with Fluttershy and the rest of the six. Since Discord is my favorite villain of the series thus far, I'm very eager to see what they do with him this season. And Meghan McCarthy already revealed that him singing a piece of "Winter Wrap Up" is not what they meant when they said he had a song so we still have yet to hear it.
One other thing that I noticed was that in the first flashback, Celestia and Luna were fighting in their original castle that we saw in ruins during the pilot. I wished I hadn't, but about two weeks prior to the premiere, in my excitement, I read on EQD that the next episode is where the Mane Six are in the castle for some reason (I think they are staying the night there but I forgot if the summary said why) and believe it is haunted by ghosts. And I read a tweet from Meghan earlier today confirming that the next episode will reveal more about the castle so I think it's safe to say that the summary was pretty spot on. And if my recollection is true about them staying the night there, the episode may involve Luna doing some dream protection with the Mane Six like in "Sleepless in Ponyville". I'm very interested to hear more about the castle though and am curious if Celestia decided to leave it because of the painful reminder it was to her about her sister's banishment. We'll just have to wait till next week (Gah! More waiting >:I )
All in all, it was a great opener and it answered a lot of questions and gave us some questions to ponder until the season answers them as it continues. I also enjoyed how it cleared somethings up about the past that didn't need to be cleared up like the specifics of Luna's banishment and Discord's imprisonment (I always wondered how he ended up being frozen in that position). Like I said, they weren't needed, but it is because they weren't needed that I like them so much because they just add to the details of the story, the characters, and the history of Equestria. I still think that out of both flashbacks, the Luna flashback did it the best because it gives more detail into Luna's transformation (story), Celestia's reluctance (character), and the expansion of Equestrian history like how Celestia and Luna lived in the ancient castle during Luna's banishment, how the Elements were kept in the castle as they were when the Mane Six first found them, and that Luna could have been one of the reasons that the castle lay in ruins in the Everfree Forest in the first place because of her battle against Celestia. It was also great that it started a season wide story arc that will constantly be answering and creating questions. If I were to give the episode a score I'd give it a solid 5/5, but I'm not one to give scores and would instead prefer a Pass/OK/Fail grade for two reasons. One, I'm not a very good reviewer and am probably missing a problem or two within the episode whether because I didn't notice it or I didn't think it was as bad a decision as more experienced reviewers might know it to be; and two, because it's a lot less complicated for me to choose between a good, mid-ground, and bad decision than base a number on decisions without feeling like I'm being too black and white by saying good or bad.
TLDR: Great episode. Set up a story arc. Expanded on info from previous seasons. Lots of humor and feels with a fair bit of action. Watch it.