@DoctorWTF
She probably hoped that as Twilight’s appointed disciple, they’d all love her in such desperate times, as has been said… which if that seems a good idea, but somewhat short-sighted in execution, with the missing steps involved, it probably is, since she’s a kid and and all. Her plan was ultimately compromised by the fact that Neighsay got away, in the end, anyway, aside from the goal she’s using to further it, itself failing at the last minute.
She seems to have something of a planning flaw in that they don’t always act like they’re “supposed to,” in how it works out, and that’s visible throughout the two-parter, like her ultimately underestimating Twilight and the others (they were never supposed to escape Tartarus), her assuming she’d be made Headmare in Twilight’s stead, instead of Starlight (though she might’ve intended Starlight to die in the “spell failed” chaos, since she helped plan the field trip), but she is pretty damn adaptable.