User blog comment:FairyRaven/Fairy Tail Chapter 335: The Time of Life, Review and Commentary/@comment-24.45.179.151-20130620190905

For those who don't know much about Last Ages: -It can reverse time itself for the price of your life. -Since its uses are in ways against how time magic is supposed to be used, it can/is considered a taboo type of magic, which is why using it leads to death.