How is damage reduction calculated?

[Torantolis]

Ironbreaker + Barkskin = Ridiculous

I actually forked up the calculation there, mixing up the amount of damage taken with the actual DR. It’s 58% when you have Barkskin active (which is huge compared to 42%). It’s multiplicative. Basically every source of DR is multiplicative in the game. Damage taken: DMG = 100 Damage reduction, source 1: DR1 = 30% Damage reduction, source 2: DR2 = 40% ActualDamage = DMG*(1-DR1)*(1-DR2) 100*(1-0.3)*(1-0.4) = 42 damage taken Actual DR = 42-100=58% DR If it was additive it would look like t…

This was a calculation that was brought up for a conversation about the changes to Barkskin when it first came up. I’m not 100% sure that it’s accurate, but it’s certainly a starting point. I’ve been basing my DR calculations on it for months, so I’d love to be told I’m doing it correctly and I’d also love to be corrected so I can do it right

More or less, I think it comes across as the largest source of DR to the smallest, but I’m no expert in the area.