Board Thread:General Discussion/@comment-6986530-20160727023152/@comment-27428960-20161012220951

I personally think that it's Arth's soul in the mud human/golem/thing. It's the explanation that clears up the most plot holes. And no, I wouldn't call this reincarnation, although arguably it could count as ressurection in the way Elluka was originally thought to have been resurrected before the Pierrot reveal.