User blog comment:NoNickNeeded/Urano Metria power source?/@comment-5268982-20130901094404

Since the caster(Lucy) of Urano Metria is supposed to be the "Ruler of the Stars" and also orders the 88 stars to shine, I would guess that the third option is the correct one. However, the whole Urano Metria thing is shrouded in mystery-why is Lucy the only one who can cast it? Why is it her only caster Magic spell? How did she acquire it again after she forgot how to use it? Why did Hibiki have it/know about it?

It is a really interesting spell, and I sort of wish Mashima spends some time explaining those questions and have Lucy use it again.