User blog comment:Leek0421/Dragon Slayers & Celestial Magic/@comment-75.172.82.63-20150501152711

For the Celestial Spirit part, Eclipse needed the keys to open it. Celestial Spirit Magic wields more after all 12 are united through 1 Spirit User. I think in the GMG when Lucy and Yukino combined their spirits to stop Eclipse. That was kind of a teaser to what all 12 could do together.