Board Thread:General Discussion/@comment-6192846-20130812010713/@comment-6986530-20140618202039

For that last question, the answer probably lies in what brought Elluka back to life in the first place. Was it becoming a vessel for the two gods that revived her? Or did Levia and Behemo see a dead, intact body placed close to their prison and take a chance as she was waking up? Was it the machinery/magic inside the Sin?

If it is the Sin itself, it's possible that it was common knowledge it had great power and could possibly resurrect the dead. It could have been something where everyone knew it could resurrect people, but that the cost was very great (like each time it got a little bit more out of control) and that was why it was forbidden. Just speculation.