Null Follow up

Wrong. It only forces a speed check for doubles while ignoring skills.

It only stops skills that allow doubles/pervents doubles.... the only thing i like about this banner this that these units will be permanent in the summon pool to get these skills

I think this skill is definitely the most meta-changing of everything on the banner. The question is just how meta-changing it will be.

For glass cannons, ORKO is still more or less imperative, and desperation is needed 2HKO. Even if you're using a desperation weapon, the only situation in which you would need null follow-up is if they're blocking your double for nothing with something like wary fighter, in which case you may as well go for brash assault because it will give you free doubles against units too fast for you and if you run into a wary fighter without DC you don't get killed anyways. Null follow-up would be too specific to merit the sacrifice.

Slow tanks are probably going to prefer guard or QR, or possibly special spiral with the idea of OHKO on retaliation (wo dao + steady breath + ignis, for example). Null follow-up does not help when getting doubled via spd.

Fast tanks tend to need QR. They do now have a comfortable answer to bold fighters because they will be fast enough to block the double once they force the bold fighter to play by the rules.

Healers obviously can just use dazzling staff (or wrathful, and put dazzle on the staff itself). If you use wrathful + null follow-up, you need to be able to tank, which I guess maybe makes sense on someone like Sakura or potentially Lissa (vs other slow units), especially with fortress def/res? But Lissa should probably use guard or QR.

That leaves one category: sweep debuffers. If you have, like, 40-43 spd so that the other fast units in the game can't double you, and you have decent mixed defenses, and you were previously dependent on windsweep or watersweep, you might have a good option here. I'm looking at M.Morgan. The problem with windsweep and watersweep is that you can only ever cover one side of the spectrum, and you also give up your player phase double by default. Now, if you can actually take a hit, and Morgan can probably take one hit pretty easily unless it's a blue with colossal atk like B.Hector, you can guarantee a debuff. Legault and Gaius, I would say, are in a similar boat, and Legault is so fast that he can probably go for something like fortress def/res and he'll be doing pretty well for himself as a debuffer. Even Sothe is potentially doing quite respectably with fortress def/res and +spd -HP. Unfortunately, it probably won't work for someone like Saizo with bad res, or maybe Felicia due to low def (which dragons can exploit). Saizo needs to stick to watersweep, which means he probably needs to steal Kagero's drink so that some vengeful fighter can't bonfire him. We can also include in this category light breath and dark breath dragons who can get into trouble vs QR tanks.

Have I missed anyone?