I believe that was just some illusionary trickery assisted by magic, but i can see it. the mention of nightmare night reminds me...for some reason I can't think of the end of that episode in cannon now...I wrote a slightly alternate ending to it as the start to a fic and now that's all i can think of...blah
Honestly, the staff didn't want her fighting the changelings... Come on.... how much fun would it be.... She looks at DJ Pon3, looks at the speakers, picks up the microphone and turns looking at the changelings with an evil smiles, then.... Yells maud'dib into the microphone with the royal canterlot voice. end of the changelings... and every window in canterlot.
Actually I was more thinking of "The Voice" From dune. She doesn't need a vocalizer but... i'm sure DJ Pon3's speakers would work well enough with her voice to... you know... shatter exoskelitons, walls, solid rock...
I love this comic series. Because this is EXACTLY how I picture Luna in my mind: as a total badass who will eff you UP. Even the last panel, where she's like, "screw this, I'm going back to sleep" is so perfectly HER (in my headcannon, at least) that I just want to believe this is actually what happened.