Too bad Cozy Glow went power-crazy. The ability to strategize any situation like that would’ve made her a GREAT lawyer!

@Dogman15  
His personality is different also

@CORDZ2000  
Which could explain why his voice was different. (Real-world reason: Instead of Jim Miller, Alvin Sanders was cast.)

@DerpyFast  
Ive heard theories that sombra was never actually truly brought back

@Background Pony #9DAA  

 
So if they had been forced into a situation where they had to kill Cozy Glow in self-defense, you would have zero issues with her dying?
 
Also, The Elements had the power to destroy Luna and Sunset Shimmer’s evil sides. They turned Discord back to stone, and they weakened Tirek to the point where he could be sent back to Tartarus. Twilight was controlling The Elements directly, and she didn’t do any of those things; she just disintegrated Sombra where he stood. Pretty sure that was the first time Twilight ever unambiguously killed someone, too.
 
The double-standards are the most transparent thing in the world.
 
The Trio get turned to stone, which just puts them in stasis. They can be released at any time: “They were executed! This is such a horrible injustice!”
 
King Sombra is literally killed when non-lethal options existed: “Meh…”

@Vivace  
Sombra’s death was an act of self-defence on the Main 6’s part as he was attacking them. The trio, meanwhile were depowered and defenseless when Celestia, Luna and Discord turned them to stone, which made it practically a summary execution. It also doesn’t help that one of them was a child.

@DerpyFast  
Isn’t it more odd that Sombra’s fate doesn’t haunt Twilight as much as these 3 do when she and the reMane 5 directly disintegrated him but didn’t petrify the T3 themselves, nor order it be done?

@CORDZ2000  

 
It is implied when Discord said that he could still “hear what Celestia says” while he was still encased in stone.  
-> Why only mention Celestia?  
It is CLEAR that SHE was talking TO him (previous to taking him to Sweet Apple Acres).
 
While it could be just a case of “If you can hear me, please do not escape/rampage when we release you” (followed by the same “plan” she explained later again to the mane six).
 
BUT!: It makes more sense for him to actually follow along with it IF she offered him SOMETHING in return.  
Or even better, if she ASKED something from HIM (to be done much later), with his “good behavior” as SILENT PROOF of this “implicit agreement” (this way he could say without lying that “he never promised anything” to her).  
-> We know Discord is partial to making DEALS, from his later “partnership” with Tirek in the Season 4 finale.  
—> Bringing those flowers TO Celestia (at the end of the S4 finale) may have had a deeper meaning (perhaps those exact flowers were growing next to him when she offered the “Deal”).
 
The “Deal” of Celestia was basically allowing him to (indirectly) DESTROY the Elements of Harmony (him being free FOREVER), but only AFTER she manages to convince Twilight to replace her (so she can be FREE from her endless task of controlling the Sun & ruling Equestria).
 
(As caution) -> Celestia placed a spell that specifically prevents Discord from casting ANY spell on the Elements (aparently he can still touch & move them manually, just not use magic). She could “lift” this spell at any moment without anypony else knowing.
 
Things went really fast as soon as Celestia & Luna “announced” their retirement in the Season 9 finale.  
Discord just assumed that Celestia had already left the “ban” on the destruction of the Elements, so he started his Master Plan (not expecting Sombra to do the work without being specifically directed, but he likely already planned something like this for later).
 
[ Because Discord does NOT actually wants to rule Equestria anymore (having “conquered” a specific pony´s heart is already enough for him), he wanted to “test” Twilight for his own amusement, forcing the villains back to their cells IF she would fail at it for some reason. ]

@Argamis  
They had the elements of harmony against discord, what deal?

@Background Pony #9DAA  

 
She is like a sapient cockatrice who just reached maturity.  
-> That kind of power requires not just “guidance”, but moral rightness & strength of character (it reminds me of filly!Applejack´s thirst for power & control in that terrible hospital episode).
 

 
I also agree about the “release danger” factor was (in principle) equivalent to a Discord´s Rampage.  
This is why I think that Celestia made a PACT with Discord BEFORE bringing him to Sweet Apple Acres [even if she could not hear him agreeing or not, the simple fact that he did not revealed it to the mane six is by itself better than a “Deal!”].  
-> The way Celestia looked at him in anger righteous fury on the S9 finale was enough for me.

@jdb1984  
You’d first have to find many images showing “cutie mark acquisition” to start a new tag, in my opinion.

@Dogman15
 
Why don’t we make it and spread it around? It got “Victorious Villain” widely used.
 
(Just a sidenote, victorious villain is when the villain wins and is enjoying the defeated hero/ine in a sexual way.)

Poor filly doesn’t realize just how much guidence she needs for a talent like that.
 
 
@Argamis  
@Background Pony #0F37  
They are no more dangerous to release then Discord was.

@DerpyFast
 
she didn’t release them. anyway I was just trying to help. I don’t actually care if she feels guilty about sombra or not.

There should be a tag for “cutie mark acquisition” - whenever an image or GIF/clip shows how a pony got their cutie mark, canon or fanon, official or OC.

@DerpyFast  
I think you answered your own question. What’s the point of trying to reform someone that’s already completely gone?

@Argamis
 
ugh, they even gave cozy glow super powers
 
I really need to get around to finishing season 9
 
you’d think they’d at least have the decency to petrify her as an alicorn princess.

Argamis is right. Twilight could not take unnecessary chances with the Terrible Trio and will thus see if these can be reformed before it becomes possible to release them from the petrification. Also, I believe that the dreams and her actions to be able to learn about the trio are dictated by the Harmony Magic that we know is not dead. Sombra destroyed the tree, but the magic behind it has not gone away, instead it continues to exist. And it would of course be logical if the Harmony Magic should think the Terrible Trio should get a chance. As an alicorn, Twilight will be sensitive to possible dreams about the future. She saw what would happen if the petrification were to continue indefinitely. Sooner or later, the three would die when the statues are exposed to the ravages of time.
 
So far we see a logical and simple background for Tirek’s beginning of his life as a villain, a possible sad background for the young Chrysalis who has not yet perceived herself as a monster who can never make friends, and a free interpretation of Cozy Glow’s sad fate .
 
Here Cozy had learned how to manipulate others, and become skilled at handling tricky developments of a given situation - but the most important thing for her is that she got a sense of satisfaction, power and self-confidence, and thus had come to believe that her talent is all she needs. She would have become a very skilled politician in throat-cutting political activity. It also happened by chance, a simple idea to spread discord has become much more. Then it is no wonder that the magic responded to it by giving her the cutie mark. But she is not evil or ruthless here, just a child who had started on the wrong course.
 
And when it comes to Sombra; I do not think he is dead. Discord can not really resurrect the dead, and the symbol used to bring him out suggests that he was summoned from possibly the Limbo to which he may have anchored his soul. Although the old-fashioned magic of ponies was fatal to him, it is certain that he was once again sent back to the Limbo - for the third time. Not many villains have “died” three times as Sombra. But he is probably now permanently stuck in the emptiness - until someone brings him back.

@redweasel  

 
They CAN undo the petrification at any moment (that was never the problem), the reason they would NOT do it is because of the risk of them escaping at the first oportunity:  
. Chrysalis has both a horn & arcane magic -> She SHOULD be able to cast self_teleportation.  
. Tirek has horns but no magic (he COULD absorb Chrysalis magic if she wills it).  
. Cozy Glow knows how to use Glyphs/Runes/Seals to cast ANY spell.  
-> Tirek & Cozy Glow both know the spell to create “windows” connecting two different places (from the Canterlot Castle´s Throne Room to either Tartarus or the outside of the Castle).
 
Then, the problem WAS how to “give them an oportunity” in a safe way (Twilight finally figured out).

@redweasel  

 

 

 

 
Sombra had a body in “The Beginning of The End”. Either way, you’d think doing this to him instead of giving him the chance to redeem himself would also haunt Twilight.  

 

 
No, she thought that’s how Celetia was going to punish her.

@DerpyFast
 
I don’t think they can release them, in this comic’s interpretation of events. it was a change that nobody knows how to reverse, which is totes fine because who would ever want to reverse it? and then oh shit twilight did it to herself what do.
 
can’t say much about sombra, except that he was already smoke before they smoked him (ha). I think the idea is that twilight can do something about it, so the fact that she doesn’t haunts her, until she gives in and does. plus unlike sombra, those three actually were learning about friendship.
 
wasn’t twilight about to punish herself and maybe never get to see her friends again, after the “want it need it” spell? she thought she was going to be sent back to canterlot, but her friends were the only ones who protested that.

Been reading through this. A couple of thoughts:
 
Sombra
 
The Legion of Doom are just in stasis. They could be released at any time if she feels like giving them another shot at redemption. That’s what Celestia did with Discord, and it worked. Not only was Sombra never given a chance, he’s dead; Twilight and her friends destroyed him. If you’re going to approach this from a guilt perspective, you’d think she’d be more haunted by the thing she can’t undo, especially considering he was a dark reflection of Twilight. But it’s not even mentioned. The elephant in the room is that if you mention Sombra, it introduces the idea that not everyone gets a chance at redemption, and that not everyone can be redeemed.
 
Twilight’s characterization
 
I’m 100% willing to accept that Twilight would come up with an idea like this, and it’s an effective tool for exposition. But how we get there is completely out of character for her. Twilight is not the sort of pony to punish herself. If Twilight fails, her friends never get to see her again. She would never do that to her friends, especially considering that it was the realization of how glad she was to see her friends that re-activated The Elements in the first place. She would also never turn her back on a task entrusted to her by Celestia.
 
Lastly, there’s a pattern to how Twilight approaches problems. She starts with a straightforward approach that relies on raw ability (casting the wing spell on Rarity, unleashing a massive magic attack against Tirek), then she tries a more strategic approach (casting the easier cloudwalking spell, trying to catch Tirek off guard). Her most ill-advised ideas are usually only a last resort (the “want it need it” spell, or stopping time). If she’s that bothered by The Legion not being redeemed, why didn’t she just release one of them and give them a chance at redemption? Why immediately go to the idea which, if it fails, means she never gets to see her friends again?
 
The machine is a legitimately cool concept. I like that.

I did have my suspicions about why Cozy Glow’s cutie mark was a chess piece. Something like this was my headcanon, too.

Makes more sense then breaking up the friendship considering what we’ve seen her do in canon. This still isn’t going to end well.