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Masterkiller
11-19-2009, 09:18 AM
I'm trying to calculate the effect of an additional 25% armor and 2% damage reduction. It should all be multiplicative so it shouldn't matter the order?

I am receiving a 20k phys hit as a blood spec DK and I want to see what the difference would be if I was Frost with UA activated. Can I simply reduce that by another 2% (Imp Frost Pres) and then the additional armor reduction (not sure what 8k armor reduction is)? Or will I need to reverse the order to find out the unmitigated damage and then re-calculate the damage reduction?

1) For reference, what is the order of incoming damage?
2) How much reduction does each point of armor provide? I can calculate 8k armor from there.

Thanks

Satorri
11-19-2009, 09:32 AM
The order doesn't particularly matter because, as you said, it's multiplicative.

That said, you might like to peruse this:
http://www.tankspot.com/forums/f14/55944-survival-numbers.html


As for your interests in Frost vs Blood, I'm going to side step the numbers (hopefully this will offer the tools to do that math yourself), and get to what I think is more important.

Frost will take less damage than Blood, period. What is lost and is hard to quantify, is the self-healing from Blood.

The difference may actually be more severe than you might think. I did some tests in Ulduar, blind studies on healer perceptions, and compared parses. The results were something to the tune that, the healers felt like I took less damage as Blood, where parses recognized that I actually took upwards of 20% more overall (that is *NOT* the actual difference with just the passive buffs though mind you). The self-healing from Blood, especially in the hands of a user who's experienced, will be a significant value on the apparent damage taken.


*Also, here is a handy web app, to quick-calculate reduction from armor: World Of Warcraft Armor Damage Reduction Calculator (http://rehfeld.us/wow/damage-reduction.html)

Masterkiller
11-19-2009, 12:14 PM
That web app is awesome!!!

I'm a big fan of blood, but I wanted to compare the advantages of blood to frost on a ToGC 25 Impale + Impale tick + melee swing combo (within a second) that occurs sometimes.

With 32k armor you receive a 25% armor bonus of 8k or an additional 4.83% phys damage reduction when you activate Unbreakable Armor. You would also receive an additional 2% reduction from Imp Frost Pres to total 6.83% reduction.

Holy smokes reverse engineering how much the unmitigated damage was from the mitigated result is hurting my brain...

So if the original hit was 20,000 and our reductions are:
8% Frost Presence
5% Blade Barrier
65.7% Armor

then the hit should look like this where X is the hit prior to reduction:
20,000 = (X-(X*.08) or X = 21739
So prior to Frost Presence the hit was 21,730. Now to find out prior to Blade Barrier the hit was:
21,730 = (X-(X*.05) or X = 22,883
Prior to Armor:
22,883 = (X-X*.657) or X = 66714

So Blood spec with 32k armor reduces a 66,714 hit to 20,000.

Now for Frost with UA up.

10% Frost Presence
5% Blade Barrier
70.6% Armor Reduction (25% bonus from 32k)

Blood Result: 20,000
Frost Result w/UA: 16,770 damage
Difference of 3,230

The really only dangerous time on Gormok is a string of hit + impale + impale tick exceeding your health pool. Blood has WotN which on a 20,000 hit reduces the hit by 15% or 3000 damage to 17,000. Very similar to a single melee strike reduction when UA is up. However, the Impale itself would also be reduced by UA and Imp Frost Presence resulting in a larger gap between damage taken. A Blood DK will probably have about 800 more health and can reactively DeathStrike (I always DS immediately after Impale) to return 8k-12k health but if you are already dead you obviously cant.

I'm not aiming at pointing to one spec or the other, I was just interested in the differences between Blood and Frost on Gormok impale combo's.

Masterkiller
11-19-2009, 12:15 PM
Oh and thanks again Satorri for the math help

Masterkiller
11-19-2009, 12:37 PM
Is there a better way of taking the final damage (shown in combat log) and figuring out the original unmitigated attack amount? I was wanting to put this into a spreadsheet but Excel doesn't like circular references =/

Airowird
11-19-2009, 04:36 PM
Is there a better way of taking the final damage (shown in combat log) and figuring out the original unmitigated attack amount? I was wanting to put this into a spreadsheet but Excel doesn't like circular references =/
Circular references can be stopped by turning on the option "Iterations".
This will put a limit at how often Excel will recalculate after changing the value of a cell, thus making circular references possible, yet still accurate.
That's how I solved my Parry Hasting calculations in my spreadsheet btw :D

Wars
11-19-2009, 07:17 PM
What this post is looking at is the effective difference in damage taken and perceived damage taken. Which is more of a theoretical discussion of the application of the original question.

Blood is still perceived to be the strongest tanking tree by most healers, the self-healing part of blood, as Satrina has said, camouflages the actual extra damage.

I can't answer your questions for you Master, because I think you're well on your way to your own conclusions now, but I can say that in the mind of the healers and usually the raid leaders, perceived damage taken is usually the one that matters initially.

After that you're guilty until proven innocent. Tangent I know, but worthwhile for the thread and your concerns none-the-less.

Xianth
11-20-2009, 03:29 AM
*Also, here is a handy web app, to quick-calculate reduction from armor: World Of Warcraft Armor Damage Reduction Calculator (http://rehfeld.us/wow/damage-reduction.html)

ahh nice, i'll try to remember to bookmark that when i get home rather than always working it out by hand :D