1261. Fusion
The Elbas family could still be in the world. Noah had spent the last year of the dimensional portal in seclusion, so he didn't confirm whether they had left the plane.
Noah didn't sense anyone observing him during his hunts, but the Royals were experts in fields that he couldn't even fathom. There was a chance that they had seen his battles without alerting his innate awareness.
The cave in the seabed didn't have any defense. Noah couldn't relax there, and his mental state was crucial for the success of the procedure.
Noah rested inside the separate dimension for a few weeks and started training only after he felt sure that his centers of power had dispersed the stress accumulated in the last battle.
Once Noah returned to his peak, he began the preparation for the procedure.