User blog comment:Miskos3/Fairy Tail Episode 249: Tartaros arc: The Celestial King vs. The Underworld King, Review/@comment-180.191.130.34-20150906035140/@comment-26287497-20150907004639

I have a theory too. Layla summoned CSK and made her terriblky weak leading to her death because instead of a key her life force was used. it could happen the in the year layla retired from being a csw or the year she died.