User blog comment:KnocknickKnock/9 gates + master of the celestial realm/@comment-24066070-20131208182752/@comment-7418318-20131213184307

Lucy is far from the first person I think about when hearing the words "plot armor".

When she's allowed to actually fight (rather than just being decoration) and wins, it's usually not because of Nakama power-ups or plot armor. Urano Metria is really the only instance of an unexplained power-up, but exactly that it wasn't explained leaves far more room for the "suspension of disbelieve" than "squeezing out tomorrow's portion of magic".

In Urano Metria's case there are several logical possibilities for the spell to gather energy from sources other than Lucy, which I don't want to go into here. Though I made a blog about this several month ago. Or it could just be an extremely energy-efficient spell that, if cast perfectly (which she would have done, thanks to archive) will cause a lot of damage even with very little magic power fed into it.