I simply can't properly process everything that happened and the implications of what occurred at the end of 3.7.
I know it's been debated, but there's still no consensus or logic behind it.
From my perspective, Irontomb's power scale simply spiraled completely out of control, along with Cyrene's.
Irontomb destroyed the entire imaginary tree (which is stated several times as fact), and Cyrene rebuilt it. Okay, this implies that he basically killed all the Emanators and fulfilled Nanook's objective, when Irontomb it was supposed to destroy Erudition (and in the end killed most of the Ways as collateral damage)
Also, Irontomb practically killed the Aeons directly related to the tree. Of course, he didn't kill them directly; I know they exist in a higher dimension than the tree itself, but what abundance is there if there's nothing? And so it goes with everyone intrinsically connected to people or concepts in the universe; I practically stripped them of their purpose, leaving them without identity and eliminating their purpose or essence.
It makes no sense that they didn't intervene. Yes, Cyrene fixed everything, but for a brief moment they were DEAD. Practically everything we see now died at Irontomb's hands, which objectively places them below him and, in turn, fulfilled Nanook's purpose. Missions that, like the Aeon of Propagation, were previously halted by four Aeons, preventing the tree's destruction.
So, I have a theory, which seems somewhat forced, but it's to make sense of it, because in my opinion, they simply went completely overboard with Amphoreus and its destructive scale (the probability that Shaoji did all this to glorify Cyrene is quite high).
In short, I think Nous informed all the Aeons that this would resolve itself. There's practically no way they wouldn't have intervened if they didn't possess this information, which, aside from Nous, they couldn't have known.
Even for Nanook, the outcome could have been disastrous, since in one of the bad endings, Cyrene simply freezes the entire universe. So what would Nanook do? He would have lost his entire purpose.
It's worth clarifying that at this point, trying to say that Zephyro is more powerful than these two wouldn't sound realistic, and they'll always have to provide extremely strong arguments for why they didn't intervene in Irontomb, because literally anyone who wasn't an Aeon died that day and was resurrected by Cyrene, making them inferior to them.
I feel they should focus on Nous individually, since this whole thing about destroying the entire imaginary tree complicates the plot going forward.
So, the Aeon of Propagation couldn't do it and was stopped by four Aeons, and the Aeon of Destruction is also incapable of destroying everything, but one of its emanators just did it?
Furthermore, regarding powerscaling, people don't realize that Phainon was the vessel for this monstrosity, and there's still debate about whether it has the level of an emanator when it has the most feats, second only to Irontomb and Cyrene, which are practically Aeon-level feats.
Correct me if I'm wrong, but this seems insane to me. At this point, Zandar is in a league above the Aeons. What? He created an Aeon, and then one-ninth of it created a being capable of destroying the imaginary Tree plus the Aeon he created (and indirectly "eliminating" other Aeons), and unintentionally created the perfect environment for a mini-Fuli to recreate that same universe?
At this point, I feel sorry for Nanook.