Well, I guess she bombed the test. Thus confirming Celestia’s assertion.
 
So everything worked out fine! Ha ha ha!

@Impious Guy  
My headcannon is that Luna is basically an Alicorn atom bomb. She don’ t get involved in crisis like the changeling assault and Sombra’ s return cause the collateral damage would be davastating.

A golem? Sure thing. >:3

That’d fit well with the “Sombra was once Celestia’s or Luna’s student” theory too. If he was a student of one of them, he’d be spending alot of time around Luna one way or another, it’s not unlikely a relationship would form. Then after the betrayal he committed that could have thrown Luna into a downward spiral.

Or maybe Sombra was once somepony important to one of them, and Celestia didn’t want herself or her sister to get involved with that dirty business again.

Dupe of >>165717

With this, that would make perfect sense. Especially if for some reason Luna let it slip that she was behind Chrysalis some how. Maybe she’s just a really bad actor.
 
But, I prefer the theory that Sombra had something to do with her downfall, and Celestia didn’t trust her to be in the same situation again.

Hence why Celestia didn’t let her go to the Crystal Empire instead.
 
“Twilight needs an actual test this time, and you certainly aren’t responsible enough to go in her place.”
 
“But… I- Yeah, you’re right.”

That too.

Or, Luna’s trying way too hard to prove herself, and by recklessly endangering everypony in Canterlot she merely proves that she isn’t prepared either.

@d715  
Plans fall apart, especially when you’re dealing with someone like Chrysalis as an “ally”. Luna may have underestimated what she was making, or instilled a drive that led to a result she wasn’t expecting.
 
Ex: Making Chrysalis clever and with some knowledge of resources available to Twilight, such as the Elements, things an inhabitant of the world would know about. While also giving her the drive to conquer Canterlot using disguise and an army. But something went wrong, such as a control measure slipping, or Chrysalis going off the rails and poking around to learn things she wasn’t supposed to so she could cut Twilight off from support from friends and, in time, the Elements. She probably had meant herself or Celestia as a final control measure but that back fired too.
 
I.E. Not really stupid, but more along the lines of a mad scientist who’s monster goes out of control.

@d715  
Or, y’know, it confirmed Celestia’s belief that Twilight was not prepared.

@RagnorakNow
 
Twilight lost the battle, it was Shining and Cadance that saved the day. So Luna’s plan blew up in her face. I’m with Guy Luna’s a dumb fuck.

@Impious
 
Well at least it goes to show the Elements of Harmony can’t always be our reliable Deus ex Machina right?

Luna, are you fucking dumb or what.

^Well she was nowhere to be seen when things were going down. She could have been deliberately vanished to see how Twilight would act.

This reminds me…. they better explain that black starry book something this season

@atryl  
Nor is there anything suggesting this.

NOOO SHE IS LETTING YIVO IN!!!

Uhm.. No this is just a theory. I didn’t find clues that could go against this idea :)

@RIG
 
Don’t think it’s his planning. Comission… maybe?
 
I know he has PLENTY of those :P

This is something i commonly expect Luna to do.

Dammit, Luna… I told you not to mess with nature. But did you listen? Nooooooo.

Atrul…what are you planning?