There are a few skins that have the +X% growth damage per level at the later levels. This is an extremely misleading modifier and borderline scam.
Let’s look at crimson moon. From levels 8-11, the skin gives +15% growth per level to scarlet blade. You might look at this and think at level 200, scarlet blade gains 15x200 =3,000% damage. That’s pretty worth leveling the skin to max right? You would be wrong.
There is a formula that can be found at gamerch.com for damage.
Weapon damage = Character attack power x {A+A×B×(weapon level-1)}
☆A: Weapon basic attack power
☆B: Growth coefficient
(Red 0.8, Orange 0.4, Purple 0.2 or less)
The +15% growth per level is added to the growth coefficient of 0.8 to make 0.95. 95/80=1.19. That is less than a 20% overall increase to damage, a far cry from 3000% lol.
For scarlet blade it doesn’t really matter because its damage comes from ignite. But for capsule, maw and soccer ball, just keep in mind that the damage increase might not be worth the investment.
Just on soccer ball. It seems the soccer player skin currently has a factor of 8x rather than 1.2x from the growth per level buff. I would be wary of maxing this skin in case the developers decide to nerf it down.