Question about skill modifiers and weapon damage

I hope someone can help me here. I’m wondering how exactly the application of skill modifiers happens.

Using a 16/16 Primal Strike as an example:

215% weapon damage
210 physical damage
115-198 lightning damage

Then lets say we apply the Thunderous Strike modifier, which does the following:

Total damage modified by -35%
-75% Weapon damage

The total damage modifier is easy enough to calculate at the end, but how does the weapon damage modifier apply?

Is it additive? 215% - 75% = 140%
Or is it multiplicative? 215% * 0.25 = 53,75%

Thanks :slight_smile:

To my knowledge, almost everything is additive.