"What kind of failure would it be safeguarding against?"

"I don't know enough about the Avatar to be have a solid guess. Do you have any special powers in regards to spirits?"

"Yeah, some. They're a little softer and fuzzier than I like my powers to be, but they exist."

"Maybe there's some hidden version that are less soft and fuzzy that you can get by hacking them just right and the spirits want to be able to shut the Avatar down hard if one ever finds it."

"...Disturbing, but not implausible."

"Not really the sort of thing that's safe to test, though."

"Yeah, let's not."

"I'd say I like our powers better on the grounds that they're less plausibly disturbing but no one has any idea how they work, it's highly unlikely but not impossible that every time someone gets superpowers a baby dies or something."

"Not enough people getting powers to see past noise in the mortality rate?"

"I don't know, I pulled that as an example out of thin air; there's no reason to think it would be that and not some less statistically visible creepy thing. There isn't actually any particular reason for there to be a creepy thing, but since we don't have a clue how it works..." Shrug.

"Yeah, that sounds unsettling."

"And the fact that the reincarnation thing is happening suggests that there's more we don't know about what it does, let alone how it works. Back about six and a half decades ago some reclusive inventor type made and sold a bunch of power amplifiers, but he stopped after...a supervillain got their hands on one and was obnoxious with it until it broke, and no one's been able to figure out how they work since. I think most of them are in museums or private collections right now."

"Weird. They couldn't be reverse-engineered? Nobody went through his notes? Is he still alive?"

"They could sort of be reverse engineered? You could make all the same parts and put them together and make a new one. But no one could tell why it worked. And people were understandably leery about the possibility of more villains getting their hands on them."

"Oh, I see. Missing theory, not missing manufacturing knowhow. Huh. Some bending get more powerful at certain times - firebenders like daytime and comets, waterbenders like full moons and night, for top performance earthbenders rely on some geological properties unless they're specially trained as sand or metal benders, airbenders oddly enough like high altitudes but it's much less obvious for the latter two than it is for fire and water."

"And presumably during the daytime all of the firebenders get stronger etcetera, so it presumably wouldn't be too much of an advantage for any one side in a conflict."

"...Well, if the sides are mixed, yes, but historically that's often not the case. We're integrating more, but there's still an Earth Kingdom and Water Tribes and a Fire Nation. Airbenders were nearly wiped out and are no longer an obviously distinct ethnicity, but they've reclaimed some temples and stuff."

"Oh. That was not obvious. Any idea why you have an Earth Kingdom and Fire Nation and whatnot?"

"Bending's hereditary - not everyone has it and it can skip a generation but you don't get a long line of earthbenders turning up a waterbender - and dragons live in one place and badgermoles another, flying bison and the moon both kinda get around more but waterbenders were the only people who could live at the poles effectively and wanted to and airbenders were doing a monastic nomad thing rather than interbreeding with anyone else. Also, being able to bend and not having a competent teacher around is thoroughly dangerous, so populations clustered for that reason too - or all died in fires or whatever."

"Ahhh. That makes sense. So the fire people are stronger in the daytime and the water people are stronger at night and the earth people and the air people have a bigger home turf advantage than usual."

"I don't think I'd describe airbenders as having a home turf advantage, but otherwise yeah that's about it."

"Interesting. Well, jury's still out on which system I like better until I know more about the one in my world, but one of the nice things about the reincarnation thing is that if we ever find out what's going on I'll probably get to know."

"Lucky you."

"The downside is that if your enemies are reincarnating too you can't ever get away from them forever. And I don't just mean killing them, putting someone in jail doesn't work as well when suicide is an actual means of escape."

"Oof. That does sound like a problem if they prefer being babies again to being prisoners, which probably depends on the magnitude of grudge and quality of prison."