I got my both kage SR pretty late when they were out of meta already, I've literally never been able to use either of them with success in current state of the game, so thats why having 4* restriction is disappointing to say the least. As people mentioned, regular skillbooks are easily countered right now, even if that 0.01% of playerbase can actually get them. Once (if) he gets mutations released, 4* limit is a paywall that vast majority of players, including majority of spenders simply cannot pass (@Tobei, his frags are offered only in ingot related events or spend 25-35k ones, hardly ever frag by frag like sasuke). If mutations actually go live, that means general intention of Ay being owned by highest powerhouses (since vs mere mortals they can win with anything anyway) goes to rubbish bin. Unless it's our usual "pay a lot to get short term early access" agenda.

Fully upgraded ay 4th with skill experiment passive shines in 1v1. Thats all he does.

What about sasuke susanoo skill experiments? God tier 2v2 and 3v3.

Danzo's experiments? Pretty much poor man's susanoo itachi for almost free, for everyone, most versatile (except EGF kakuzu).

EGF Kakuzu experiments? Broken literally everywhere. Even had new ninja and assist link designed specifically to counter him.

Edo deidara experiments? Another god tier 2v2, 3v3.

I'm obviously aware that those books(and experiments) arent released yet, but since discussion appeared during Ay who starts it all, it might be worth to think about it NOW how things will go, instead of doing emergency fixes.

Propably more to come in the future. Obviously its easier to get event ninja frags than treasure SR, so are they all going to be put behind a paywall? If it's only balance issue, why not deactivate skill that makes them broken and allow playerbase that farmed for ages to get them to actually use them? And if it's a matter of everybody knows what, just make it 5* restriction, disabled mutation and open skillbooks for frags, so we all know why it's the way it is. And honestly how bad would be just not use those restrictions and let that chaos reign? It's already like this, just with different teams. You always win as long as you are stronger and faster unless you meet your hard counter. The same will go for them.

Also: lately implementing new ninja skillbooks at this rate in CN is powercreep trend the same way as implementing new ninjas is one here. Most of the time people won't even manage to get one and there are already 4 new ones (except for people who instantly buy anything thats new every week, kudos for you guys who are content creators lol). If it's balanced you are concerned about, youll propably have to change half of the game that is yet to come tbh. Meanwhile we just want (accessible) new content. And competitive people, after all this time actually know what's about to come and how to deal with it.

Just my thoughts, hope they actually managed to highlight some of the issues.