While the egg was one reason, there were also other important factors like the fact that his current shadow affinity has skyrocketed, especially after he had fought with so many of the Umbra's hand acolytes.
There was a high chance that he might be able to find more shadow affinity monsters, which would only help him further.
Besides, he already had a part of the legacy, Umbra's lesser shadow magic. Combined with everything else, he would only be losing out if he did not enter the legacy at this point. Whether or not the First was laying some sort of trap inside for him, this had been his plan all along.
Now it was time for him to finally enter the legacy and see what the whole deal was about. There was no way he was going to back away from this. This wasn't some optional detour. This was the doorway he had been aiming for since the moment he first learned about Umbra's Hand.
Trap or no trap. Preparation or ambush. It didn't matter.
