With a rebel yell, she cries, "They're all gonna die!"
Lydia is in Eichen House in an apparent catatonic state until someone's very big needle comes very close to her eyeball. That'll jog anyone out of catatonia, even in...a dream?
Unless we've missed an awful lot since the end of Teen Wolf Season 4, we're making a wild guess here and assuming the first six minutes of Teen Wolf Season 5 occur in Lydia's mind. Not only does the general evil feel of the scene give off that impression, but the return of Aiden at just the right moment adds to it.
Whether it's real or not, we all know if Lydia has a vision of all of her friends dying, they're pretty much up for slaughter. Additionally, if she's really learned all of those wicked moves, she's going to be really badass. It's about frakkin' time!