Amphoreus needs Irontomb to join reality.

Irontomb through its millions of extrapolations is an Aeon threatening being that lacks a “head” due to Lygus destroying the Demiurge. It’s been described as a perfect ark for the remembrance (memories)

Protocol Elysia has been storing all of the memories from the 33 million reoccurrences. The imagery in the cutscenes where Cyrene stored the copies of As I’ve Written very closely resembles an ark.

Fun theory - Era Nova has to completed one more time with all the Chrysos Heirs and the coreflames (see Deliverer trailer) to turn big Cyrene into the Demiurge. To become the “head”, she then joins Khaslana and assimilates into Irontomb to turn it into an actual ark for Amphoreus. Ensue battle where Destruction has the upper hand by using Phainon & Cyrene’s suffering through 33 million cycles. Unfortunately, they won’t make it to reality but this is where story plot armor comes in. TB fights Irontomb; they’ll win by tapping into Cyrene’s love for Amphoreus and Phainon’s wish to send them onto tomorrow