@RIG  
celestia and luna turned him into a black fartcloud. at the end of the premier he regained enough magical power from everypony’s fear or whatever to rebuild his corporeal form, and then it was obliterated, but you can’t kill smoke!

@SeraphimDawn:
 
Kirby’s obliterated Dark Matter MULTIPLE times, and he keeps coming back.
 
Given how Sombra represents the same sort of omnipresent threat of sorrow and hopelessness, I’m guessing he’ll be back, too.

@Psyga315  
I’d like to call him “King Recycling.” But, still, I can see Discord fighting alongside Twilight in the future.

@RIG  
Because the Crystal Heart obliterated him.  
But, Sombra couldn’t be defeated through conventional means.

@SeraphimDawn  
King sombra is dead.

@Psyga315  
May not look like it. But, Sombra may be on par or even more powerful than the Royal Sisters. He is one of those “IT JUST WON’T DIE!” type of menace. That was why Celestia and Luna sealed him rather than outright destroy him. The princesses may have sustained tremendous damage during their fight with Sombra. The Crystal was unreliable due to the emotional state of the crystal ponies during that conflict.
 
I personally think the Elements weren’t enough to stop Sombra as he was pure evil.  
Please don’t hate me for saying that.

@JDEzekude  
And were refused to be used to fight King “Wasted Character”

…Wait, when was this a good idea?
 
Girls, I’m starting to think this isn’t a good idea.

@SeraphimDawn  
Oh yeah…Considering that the Elements of Harmony were compromised by the Changeling Swarm.

inb4 Discord wakes up with a headache.

@Prof.NightJack
 
Probably like this
 
http://www.youtube.com/watch?v=O9zmy1ZRzU4
 
Luminous Arc!

AJ and Rainbow Dash don’t look too happy about bringing back Discord.

@SeraphimDawn  
I think you mean Mega FRIENDSHIP Nuke.

SeraphimDawn:
 
So much harmonious magic that it would disintegrate everypony.

^{Rainman voice}  
Definitely episode 10 spoiler. Definitely episode 10.

Just out of curiosity.
 
What do you think will happen if they channeled the power of the Elements into the Crystal Heart?  
Mega Love Nuke?

ALL MY UNIVERSES JSUT EXPLODED

Believe it or not. But this is probably the first time the Elements actually appears since all the way back in Return of Harmony.

I’m sure they’re not so stupid that they’ll release him without limitations.

dis gon b gud

So they just let Discord out?

They have the elements with them, so shut up, Trick.

Never generate a magic field that’s bigger than your head.