Board Thread:Theories and Speculation/@comment-3001903-20160803001752/@comment-734582-20160803114147

Ravenlot 27 wrote: Once I was also wondering about this question, and Rinne Tensei isn't the only one of it's kind. I mean, it should be questioned if the ET-shinobi (basically, an immortal zombi) could use the techniques which usually take the user's life to as a price without this drawback. Such techniques include not only Rinne Tensei, but at least Eight Gates Released Formation and Dead Demon Consuming Seal. The eight gates would probably have no drawbacks. The big question is whether the Edo would be subject to damage from the technique. After all, Hanzo could still be incapacitated by poison. This means that while the Eight gates user wouldn't die, they likely would be subject to significant damage.

Dead Demon Consuming Seal would almost certainly work. The Edo however would simply be sealed in the demon's belly, ending the technique.

For these techniques we already know what the price is, and with Edo Tensei we can guess the effect. Rinne Tensei however trades the life in a guaranteed way, even though the soul etc is still there. So what is it exactly that pays the price?