Is there some % cap for ABC bonus? Or Does We have to calculate based on our Personal ABC % rate?
I wanna figure how close I am of a possible cap for Aerial and Back to decide if I keep to invest on those bonus.
There's not entirely a cap on ABC dmg bonus. However, once you get around 60%+ ABC dmg, the amount you gain decreases by a lot. You could keep increasing it if you'd like despite the gain being minimal, or you could aim into lower percentages of ABC dmg you have in order to balance them all out. If anything, it's a soft cap of sorts.
To go a bit more indepth on what has already been said, ABC and Empowered dmg in this game start getting deminishing returns from the moment they they go above 0%, this also applies to some other things such as crit rate, cooldown reduction and even attack speed even tho for attack speed its shown in a bit of a different way.
At 20% you only get 8/10ths of the value you were supposed to get, so for example if you have 20% aerial damage and you get a tune that gives you another 10% you now have 28%. This keeps going forever so technically the cap is 100% but the only way to get that value would be for you to get an item that gives you exactly 100% aerial damage from base stats otherwise it would just keep rounding out to 99.9...% regardless of how much abc you get (so long as its less than 100% in a single stat).
The formula to calculate the deminishing returns is Current % + [New % x (1 - Current %)], current % would be your current abc, new % would be the flat value being added, so using the example from before it would look something like this
20% + [10% x (1 - 0.2)]=
20% + (10% x 0.8)=
20% + 8%= 28%