User blog comment:OverlordRocks/Why did you guys get rid of all the pages in the immortal beings catogory?/@comment-27507964-20160205174932

I looked back and it was in episode 56 that Zane was reading the book Sensei Wu was reading before he was captured. "It says here that it is a powerful relic that can trap mortals." We really don't have enough info either way to tell whether Djinn are mortal or not.