I’ve answered this quite a few times on Discord, as it’s the fastest way to receive a reply from a moderator

Ay does indeed require 4*s to breakthrough, while this is intended, this most likely is the result of what he brought in terms of balancing in CN

So while restricting his breakthrough, I’ll also add the fact that him receiving an entire breakthrough/mutation would be extremely unhealthy for the game at this juncture

Also please realize that in CN, the mere attempt to have him above 3* is extremely difficult and outright expensive (He’s not offered in incentives, compared to our version)

Additionally, we allow fragments to breakthrough.

Different systems, result in different restrictions. As much as I can understand the need for consistency, alterations can occur to requiring quotas.