Every Asgardian returns. With a few more gods involved the story heads in the very distinct direction Marvel is leading towards.
Here are some valuable bullet points...
Amora loves Thor and after he chooses Sif, frees Loki to spite Thor. Skurge aid Amora, as her hitman, in freeing Loki.
A millennia ago, the Korbinites, an alien race, were rendered extinct, save one lone warrior, at the hands of The Mad Titan. The lone survivor, Beta-Ray, is left drifting in space, unconscious. Bill drifts into the sights of Heimdall, who reports the find to Odin.
Odin takes the alien in and locks him away, in the same fortress as, although a different cell than, Loki.
Meanwhile, Thor pleads with the All Father to show forgiveness to Loki and to not be hard on the alien visitor, as he may be telling the truth about the Titan. Thor speaks with his brother, who shows/feigns remorse. As well, he speaks with Beta-Ray and begins to befriend the visitor.
Amora professes her love to Thor who chooses Sif. Sif, on the other hand, denies Thor, as she is disgusted by his ongoing crush on the human, Jane Foster.
Amora plots to devastate Asgard alongside Loki, whom she plans on freeing, to spite Thor. She is aided by Skurge, who will do anything for the woman he loves.
As a distraction in order to free Loki, Amora sends Trolls, led by Ulik, to attack the kingdom on the day Odin's greatest protegee and warrior, returns from a 100 year-long battle in some realm or something.
In the melee, Beta-Ray is freed by Thor after promising to assist the Thunder God.
Before Amora and Skurge can free Loki, Sif and the Warrior's 3 stop them and fight. Loki yells to be released so that he may help (help who?).
A weakened Odin, readying for the Odinsleep, alongside Thor, Balder and other soldiers can barely hold back Ulik and the Trolls.
Thor battles Ulik to a knock-down-drag-out fight that rivals anything seen in the Avengers. and is clobbered by the massive Troll. Balder is to held up with dozens of other Trolls on top of him, as are Odin and other gods. They are vastly outnumbered.
Beta-Ray comes charging out of nowhere and spears Ulik, grabs, the hammer and bashes the hairy bastard so hard he knocks him out.
He raises the hammer and, with some electricity, banishes the trolls from Odin's kingdom.
Balder, Frigga, Odin and Thor check on Loki. He stands over an unconscious Warrior's 3 with an injured Sif in his arms. He is slightly weeping and kisses her forehead. Amora and Skurge are locked in Loki's cell and she's screaming he tricked her and she'll have her revenge.
Thor, seeing Sif smile back at his brother, yanks him up and tosses him in another cell. Before he can say anything Thor beats on him for a moment until he realizes silence is the smarter option.
Rounding out the end, Beta-Ray has found a home. Odin sleeps. Sif tries to reson with Thor, explaining that he was right about Loki, that, without his help, Amora and Skurge would have won. Thor says it was his plan all along, he's a trickster. Thor says he was wrong, there is no good in him.
There's a moment where Sif wants to tell Thor she has feelings for Loki and he for her. No words need to be said. Thor flies off. Sif screams "The Mighty Thor, choosing humans over us once again."
Heimdall tries to reason with Thor before letting him go. Balder, with the Warrior's 3, Sif and Beta-Ray Thor by his side now rules while Odin Sleeps. He will decide Loki's fate another day as Loki looks longingly at Sif.
Post Credits:
On Earth... Nick Fury enters a secret base. Enclave head quaters is typed on the screen so that the viewer is aware. A young Scientist alerts Fury that Project Warlock has escaped and Nova has been dispatched to find and return him. Fury exclaims "If this doesn't work Pym, you can forget about tampering with the remnants of the Destroyer to create The Ultimate you've been begging for. If Project Warlock isn't salvaged you and your assistant will be looking elsewhere for employment." He retorts "It's called The Ultron Director, and I'd like the chance..." Fury slams the door shut... Pym mumbles as he picks up a helmet not seen before this instant, "Then, director Fury, the Pym particles will stay my little secret."
Warlock is seen ripping through space.
END
Next... Captain America 2, Avengers 2, Nova
THE CAST:

Amora is Sienna Miller
Age 30
GI Joe
Character bio:
Amora the Enchantress has become a mystic witch whose apprentice, Loki has worked with her many years. She lives, not within the Kingdom, seen as something of an outcast by the King. She has had many adventures, some alongside, some against Thor and his brother. She doth truly love the Odinson but, scorned easily by his rejection in favor of Sif, her rival. This feelings lead her to align herself with Skurge.
Why Miller?
If Amora is able to seduce any man than very few can actually become the living embodiment of that kind of hotness. 4 women, Miller, Nichols, Eve and Cuthbert were the ones it boiled down to, and it so happens that I tipped the scale in favor of Miller.
Skurge is Joe Manganiello
35
True Blood
Bio:
A warrior who gain a rep as Asgard's greatest warrior, above both Thor and Balder, was exiled after fixing a battle with Amora, in order to spare her life, at the expense of his fellow warriors. From that point on, he swore his allegiance and love to the Enchantress, who manipulated him to gain what she craved, whatever that may be.
Why Joe:
At 6'5" and built like a freight train he possesses a very intimidating stature with a dark and evil look to spare. The part doesn't call for much acting ability, not to say he's not capable, but he is more than a match for the part. From
the obvious Brian Steele to the even more obvious Nathan Jones and the massive Robert Maillet, Manganiello is a better fit if only because his age is closer to that of Amora's. I know it doesn't matter, but it's just less creepy to me.
Beta-Ray is voiced by Phil LaMarr
You name it and LaMarr has voiced it perfectly.
Similar to Hulk. LaMarr would be the movements and voice, but not the model, of Beta-Ray
Bio:
Known as Beta-Ray (sounding less normal than if it were to end with a human/English name), the alien more than proves his worth as the only other being worthy (as of right now) to wield Thor's Hammer. As cool as Hulk turned out, I have no doubt Beta would be just as good. To that note, I hope Cap would never be able to pick up the Hammer to make it special to only those 2... and Odin however, I have a feeling he will.
Balder is Liam Hemsworth
22
The Hunger Games
Bio:
Away on a 100 year war leading soldiers against, oh I don't know, Dark Elves and Kurse, sure that sounds good. He returns as the prodigal son, so to say. He is the Sir Percival of the gods, with Thor being the Lancelot, I guess. He had to be put in with a reasonable explanation as to why he wasn't mentioned the first go-around.
Why:
Yes, it's so nauseatingly obvious why. That, and his height, were enough to use him. I don't think it's lazy, but instead, poetically perfect.
Ulik is voiced by Kevin Michael Richardson
Richardson voices everything from Cleveland Brown Jr. to Panthro, the latter being the voice he should use to bring Ulik to life.
Bio:
Ulik belongs to a race of Rock Trolls who live in the dimension of Asgard in the "Domain of Trolls" in Nornheim. Like all trolls, Ulik has an innate hatred of the Asgardians as they were driven underground by the King of the Norse gods, Odin, and forbidden to live on the surface. Ulik is coerced into invading Asgard, leading to a with the Thunder God. Ulik proves to be a match for Thor, as the Troll possessing incredible strength and is equipped with knuckle dusters made of the metal uru (the same metal Mjolnir is composed of).
Pym is Ewan McGregor
41
Star Wars
Bio:
A marvel staple now, the post credits tease, will showcase SHEILD's secret lab, (yes, even a secret organization has a secret lab) enclave, and it's only scientist, perhaps even smarter than Stark, Dr. Pym. It opens the door to his mystery assistant, Pym particles and ofcoarse, Ultron, which I've decided will be made from The Destroyer.
Why:
It was between him, Jude Law and Ethan Hawke. All 3 are exceptionally good actors and are different choices than the norm. All 3 would be a fine choice and fit with the caliber of actors filling out the Avengers. McGregor just happens to be grounded enough, IMO, moreso than the others, slightly, and therefor makes the perfect Pym.
Warlock is Alexander Skarsgard
35
True Blood
Bio:
Project Warlock is, as of right now, a mystery to the viewer. Is he a creation of Enclave, i.e. Dr. Pym, and his unnamed assistant? Was he found and revived?Did they infused him with something? Was he willing? Is he an alien? What are his powers and where is he headed?
Why:
He was my only pick for loads of obvious reasons. Actually, he, being my sole Warlock choice, had me contemplating using Manganiello, another True Blood alumni. In the end, though, Manganiello grew on me as a great choice and I was never considering a move away from Skarsgard, who, ironically, is following in his father's footsteps as a Marvel movie character. So, that brings the total of 2 families within the MCU, the Hemsworths and the Skarsgards.