Training dummy debuff module screws up the way buffs/debuffs stack

[ceazare]

I've been researching how the new raid debuffs stack between each other and with buffs from disciplines for Sages. When I got to Vanquish strange things started happening.

 

Vanquish benefits from Vulnerable (+5% force damage) raid debuff and a number of discipline talents, one of them is a 15% increase when target is below 30% hp. I tested other buffs/debuffs before the execute buff with my own Vulnerable debuff, but to check the execute talent I applied the Training Dummy Armor Reduction Module (the armor debuff thingy) and the numbers stopped adding up (yes I used the new damage reduction with 20% less armor).

 

After rechecking all the numbers about 20 times I realized the problem isn't with those, but with the assumption that Armor Debuff Module raid debuffs work the same way as manually applied class-specific raid debuffs.

 

Vanquish benefits from

-10% passive dot damage bonus (Drain Thoughts)

-15% dot damage bonus in execute phase

-20% damage bonus with Presence of Mind (tooltip says 25%, but it's 20%)

-10% damage bonus when it uses a Suppression stack from Force in Balance

-5% bonus Force damage from Vulnerable debuff

-2% bonus damage from 2pc Force Master set

 

Without the Armor Reduction Module, this is how they stack

(10% Drain Thoughts + 5% Vulnerable + 20% Presence of Mind + 2% Force Master) * 15% execute * 10% Suppression

or

damage = base damage * (1 + 0.1 + 0.05 + 0.2 + 0.02) * 1.15 * 1.1

 

WITH Armor Reduction Module it was different. I'll go step by step

 

1.) 10% Drain Thoughts and 5% Vulnerable:

10% DT * 5% Vulnerable

 

2.) 10% Drain Thoughts, 5% Vulnerable and 2% FM:

10% DT * (5% Vulnerable + 2% FM)

 

3.) 10% Drain Thoughts, 5% Vulnerable, 2% FM and Force Suppression:

(10% DT + 5% Vulnerable) * (10% Supp + 2% FM)

 

4.) 10% Drain Thoughts, 5% Vulnerable, 2% FM, Force Suppression and Presence of Mind:

(10% DT + 5% Vulnerable) * (10% Supp + 2% FM + 20% PoM),

 

5.) 10% Drain Thoughts, 5% Vulnerable, 2% FM, Force Suppression, Presence of Mind and execute:

(10% DT + 5% Vulnerable) * (10% Supp + 2% FM + 20% PoM) * 15% Execute

 

Not only is the final form with Armor Debuff Module completely different to the one without, the way they stack changes from step 2 to step 3 - 2% Force Master bonus goes from additive to 5% Vulnerable to multiplicative with it all of a sudden.

 

It is possible to swap 10% Drain Thoughts with 10% Force Suppression, it's not easy to check which is which without a lowbie character.

 

I chose Mind Crush because it has many buffs, but similar things happen everywhere. Overwhelmed (10% bonus to aoe damage) and Vulnerable stack multiplicatively without Armor Debuff Module, but additively with it.

 

Why is this important? Well it's not quite the magnitude as the bolster bug (lol at that one), but with 3.0 there's been a lot of theorycrafting going on for optimal gearing for classes which may have been affected by this. Hopefully it might save some headaches for anyone else who's tried to see how buffs stack... but then again it's going to make that harder because all debuffs will have to be applied manually for accurate results.

 

You're most welcome to test this yourselves and share your results, hopefully with a different class. I only did sage and spent enough time to burn two purple stims already

 

TL;DR buffs stack in a different way if you apply raid debuffs yourself or if you use Training Dummy Armor Reduction Module.