Regeneration does not make you unkillable. It does not mean that no matter what injury you suffer from, your body will return from the ashes anew.
If your head gets sliced off, regeneration or no regeneration, you're dead. Regeneration is a passive process in most cases, so you do not have to do anything to make it happen, but you have to be ALIVE for it to happen. That means if you are already dead, or receive an injury that immediately kills you (through whatever means) regeneration will not take effect, because you are already dead.
Additionally, the table listed in the rules for regeneration are the bare minimum for those control ranges. You can use jutsu to ACTIVELY increase the rate of regeneration at an ACTIVE stamina cost. Or you can use jutsu to PASSIVELY increase the rate of regeneration at a PASSIVE stamina cost on top of the -5 passive cost you already pay.
Regeneration will NEVER allow you to recover entirely from nothingness or being dead because that is Psuedo-Immortality, and is an entirely different ability with an entirely different set of rules.
That being said, because Elemental/Puppet bodies are the only thing listed as archived in the Pseudo-Immortality rules does NOT mean it is the only way. While the anchor is the standard, and will likely be enforced through all means, you can achieve pseudo-immortality through other means.
Thank you all for taking the time to read this.
