User blog comment:Omega natsu2/Chapter 384: Surfing Lucy, Predictions./@comment-24748439-20140501220627/@comment-7418318-20140502083933

Since we don't know what Lumen is, maybe.

With the way that Fairy Glitter was sealed up in Mavis' gravestone and temporarily granted to Cana through a tattoo, it's a possibility that LH is a spell and whaterever is sealed beneath the guild is just a container for it, like Mavis' gravestone was for Fairy Glitter.

Personally I don't think that's the case, but that's just opinion.