This value is much higher than the expected value. However, if wards is bugged as predicted, we add the following additional modifier.

6469 * 0.85 (wards#2) = 5499

This value is very close to the expected value.

What is the Magic Damage Bug for Vengeance Demon Hunters?

Vengeance Demon Hunters are taking significantly less magic damage than you would expect from their toolkit. I believe the Magic reduction from Proteções Demoníacas is being applied twice so the baseline damage reduction is looking like 27.75% rather than 15%. In the next section, we'll cover how the bug was discovered and how I came to this conclusion.

Discovery of the Bug and Possible Causes

I first noticed this bug a few weeks ago after primarily playing my Demon Hunter since launch when I started running higher keys on my alt non-Vengeance tanks. Spells that I could normally survive easily, such as Núcleo Sombrio or Divisão Espiritual, seemed to be doing significantly more damage on my alts at the same key level. Looking into logs, I discovered that I was taking upwards of 40% reduced magic damage on Vengeance with no cooldowns up, while on other specs, it varied from 0-15%.

Doing some quick napkin math and knowing that damage reductions are multiplicative with a few exceptions, I expected it to be closer to 25-30% using the following values: 15% from Proteções Demoníacas, 8% (additively) from Tinta Viscosa, 3% from the Pelagos trait Esquecer o Passado, and somewhere between 0-15% from Versatility.

This got me the values:


So I was expecting between 15% to 36.51% damage reduction (depending on Versatility amounts from 0-30), having the Tinta Viscosa conduit, and having the Pelagos trait Esquecer o Passado unlocked. In my specific case, I was looking at an expected value of 23.5% magic DR, but was seeing values of about 36.2% in logs.

Naturally, this led me to investigate if it was a bug with my character, or if I was calculating something incorrectly. Looking through values on my Brewmaster Monk and Guardian Druid, I saw the expected values of 0-15%, which was entirely dependent on Versatility. Following this, I went through logs of other Demon Hunters to check if they were also benefiting from this bug and how long it has been around.

It turns out, we can find a log from all the way back in the Shadowlands Beta containing this bug!

Here is an example of a log from September, before Shadowlands launched. The Demon Hunter in this log is taking 31.89% reduced magic damage with only 459 Versatility. This is 5.74% damage reduction from Versatility, so you would expect that they would be taking 19.8% reduced magic damage, but it's significantly higher at 31.89%.



Thinking back to the Beta, what changed from Battle for Azeroth that could have caused this? I can only think of a couple things:

1. Proteções Demoníacas was changed to be 3 separate ranks, which increase from 5%, to 10%, and finally 15%.
2. Tinta Viscosa was added, and Proteções Demoníacas had to be changed to accommodate for this.

I suspect something happened with this change, and the magic damage reduction is applied twice, as notably, DHs are not taking less physical damage than expected. So now let's assume Vengeance double dipping on the reduced magic damage from wards. Now the math works out like this:

In the sample log we would get the following
1-(.85*.85*.9426) = .3189 = 31.89%

32% is within the margin of error for 31.89% with some rounding.

In a generic DH's case, you would expect to see values ranging from 27.75% to ~46%, depending on their base versatility, whether they are running Pelagos, or the conduit.


This is one possible cause but there's likely other explanations. There's definitely a bug with magic damage reduction somewhere but the exact source can only be determined by Blizzard or with even more extensive testing.

How Has The Bug Affected Vengeance Demon Hunters?

Some readers will recall that Demon Hunters were nerfed quite heavily in terms of survivability near the end of the Shadowlands Beta, with such results as Fragmento de Alma being nerfed by 25% from 8% to 6% of damage taken, as well as Cutilada da Alma among others as detailed in my previous article. Many of these nerfs were due to Blizzard looking at data and seeing that Demon Hunters were not dying as much as other tank specs, so they reduced our healing as a result. However, as it turns out, the data has been skewed since the very beginning!

We've spent the past 4 months taking significantly less magic damage than expected, while consistently taking some of the highest physical damage. Due to dungeon design, with spells such as Foice Ceifadora from Mordretha, a Imperatriz Infinda or Espinho Perfurante from Hakkar, o Esfolador de Almas that deal half physical and half magical damage, our total damage taken is fairly consistent with other tanks. However, we take significantly less damage than any other spec from purely magical abilities, while generally taking more damage from melee and physical abilities. This is also true throughout the Castle Nathria raid to a lesser extent, as most of the heavy damage is physical outside of a few debuffs such as Escarne stacks on Sir Denathrius. What this has also meant is that conduits such as Tinta Viscosa and legendaries such as Fortificação de Chama Vil have been relatively devalued, as we already take so little magic damage that we gain more benefit from other conduits and legendaries.

Looking at logs as well as the current rankings, I believe this bug contributed not only to unwarranted nerfs to the spec, but allowed us to unexpectedly survive many nukes that have had to be tuned down in hotfixes over the course of this first patch.

Ramifications of a Bug Fix

A fix to this bug would probably result in Vengeance Demon Hunters taking approximately 15% more magical damage across the board, regardless of your current versatility or whether you are using Pelagos or Tinta Viscosa.

Now while it's not strictly a nerf, as it is an unintended bug, it will certainly feel like a nerf to everyone who has been playing Vengeance Demon Hunter so far in Shadowlands. This is nearly 3 key levels worth of magical damage reduction that we have been getting for free and is, in my opinion, partially, if not mostly responsible for the heavy-handed survivability nerfs right before Shadowalnds launch. Many encounters would be significantly more difficult than they currently are, and I suspect many Demon Hunters would struggle with surviving on packs or encounters that they are currently able to handle.

Conclusion

Personally, I do want to see this bug fixed despite how bad it will feel, as it is artificially inflating the survivability of Vengeance Demon Hunters and skewing the metrics. There are multitudes of issues with Vengeance at the moment, many of which get ignored because we are currently the most popular spec in Mythic+ and provide a crucial buff for raiding during this period where Havoc is not a meta pick, while maintaining enough survivability and utility to be a top pick for many guilds.

Representation of the spec at high level play is at its peak since we were added to the game in Legion, and while I would be sad to see it go down, I believe it would be healthier for the spec as a whole to be properly balanced around the expected values rather than being propped up by quite a significant bug. I do hope in the course of fixing this bug that the developers begin to see some of the other issues cropping up which I have pointed out in the past and buff the spec as a whole, along with every other tank.