I usually try to refrain from doing multiple question from the readers, but when the next morning I get about 5+ emails all asking the same question, I take that as a sign I really should address that question ASAP.
I generally have tried to keep the specifics on the method vague because to an extent it helps add to the diversity of possibilities. Each clan leader is often a legend in their own right, so there being some generic ritual where you insert statue here, recieve bacon, eat bacon, become tri-winged…just loses some of the magic in my opinion. But overall the one consistent theme in all clan leaders is an incredibly strong will and determination. It’s not a task one attempts lightly and for every success there have been hundreds if not thousands of failures.
The other thing to factor in is that becoming a tri-wing is not a natural step for being a Cubi. It isn’t a situation where one is born, becomes a Cubi, and it’s expected they will ascend to tri-wing status. There are some who theorize that being a tri-wing is actually an unnatural step. And some also theorize that such unnatural methods are what has caused it to become increasingly difficult to become a tri-wing as time has gone on.
And by some, I mean Zezzuva. She’s full of theories like that.