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// (A Brief Interlude...) 
// Story: Who Is This Lord Tirek You Speak Of? 
// by Bucking Nonsense 
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	Hey, this is Conrad.  I heard you guys were calling bullshit, so I'll take a moment to pause and explain to you what happened.
I honestly think that it is bullshit, myself, that King Sombra was able to take what Equestria considers the equivalent of a wave motion gun, and not only survive, but also use it to heal himself.  I talked to Celestia about it later, and she explained it to me like this: The Elements are able to do a lot of things, but in the end, they are tools that can harness the innate harmony within a group of ponies to do things.  If those ponies are friends or family who get along well, the elements have a lot of power.  If they're not, then the power is diminished to almost pathetic levels.  Regardless, they're objects, with no intellect of their own.  They're like a sort of primitive computer system: They can follow instructions, but you have to know how they're programmed, or else you're going to end up getting a critical error sooner or later.
And that lack of self-motivation can be a very big problem: A thousand years ago, Celestia used the elements to banish her sister to the moon because Luna turned psycho, but those same elements fixed Luna one thousand years later.  That being said, why didn't they just fix her one thousand years ago?  Simple: Celestia didn't think of using their power that way in the past.  Not her fault: She was being attacked by her sister, and had just taken a serious magical beating before she whipped out the elements.  She wasn't thinking clearly, and the elements only did as they were instructed.  Twilight and her friends, meanwhile, having no idea what the elements could do, basically told the relics 'Do something', and the relics did the easiest thing possible: They removed Luna's dark magic.  When given no clear instructions, the elements take the path of least resistance.
That was why the Elements of Harmony didn't do anything to me when they were used: There was nothing there to 'fix'.  I'm an emotionally balanced guy, and while I may have been inhabiting a total D-Bag, my being at the wheel was regarded as a good thing.  If Twilight and her friends had given the elements a clear command, I might have been in trouble, but instead, they did nothing, since they didn't detect anything wrong with me.
However, that 'Do Something' command that Twilight and her friends kept relying on can be a major weakness, and it was one that Sombra was fully aware of.  Without a very clear instruction of what they needed to do, the Elements of Harmony will do whatever is simplest to fix the problem they are used to solve.  Twilight and her friends had told the elements to do something to Sombra, but each one had different ideas about what stopping him meant: Pinkie Pie just wanted him to quit being a meanie, Fluttershy wanted him to go away, Rarity wanted him to be turned to stone, Rainbow Dash wanted his head to explode, Applejack wanted him banished to someplace unpleasant, and Twilight had wanted him to be turned into an Earth Pony, so he'd never be able to use magic to hurt others again.  Had even just two of them had the same idea, the fight might have gone much, much differently...
But since they were divided in intent, this allowed Sombra an opening to manipulate the power of harmony.  The barrier that Sombra had created for this purpose is actually quite weak.  Absurdly weak, in fact, lessening the Element's attack by an almost infinitesimal amount, unless the elements do the one specific thing that Sombra wanted them to do.  In this case, that was heal the tyrant's broken body.  So, like water flowing downhill through a channel dug in a sand dune, the elements were 'guided' into the one channel that benefited Sombra the most.  For almost anyone else, it wouldn't have worked, but Sombra is a tyrant: Tyrants are all about 'Harmony', it is just that their definition happens to be 'Everyone doing what I tell them to'.  Love and hope could kill Sombra, but as long as he had a clear intention for their power, and his enemies did not, then the Elements of Harmony could be used in his favor.  Celestia and Luna had learned this after multiple confrontations with the tyrant: From what I've gathered from the two of them, the Crystal Empire battle wasn't the first time that the royal sisters had fought Sombra, just the first one where they didn't open with the Elements...
However, while it was 'simple' to heal Sombra, it required a lot of power because of how severe the damage to his body was.  And once unleashed, the elements don't stop until the job is done.  That was why Twilight and her friends were drained of stamina in the aftermath of the incident.
In summary, that's why Sombra's barrier, in spite of the king being greatly weakened, was able to use the power of one of the strongest sets of magical artifacts in existence to heal himself, instead of being blasted to atoms, and nearly killed Twilight and her friends in the process.
Like I said, I think it's bullshit, but Sombra was an expert when it came to how the elements worked, while Twilight and her friends were novices.  Had Celestia just sat Twilight and her friends down one day and explained how they could best be used...
Woulda, coulda, shoulda, didn't.
Moving back to the subject at hand, that's the best explanation I ever got that I could understand.  I tried asking Twi once, but her version was so dry, technical, and boring that I fell asleep within fifteen minutes of the explanation.  She continued for three hours before she realized I was snoring.  Lovely girl, but when she talks shop...
Well, that's enough for this particular tangent.  We're in the middle of a story here, people!