For a long time, primary tanking theory has revolved around EHP. The concept is simple; Stack Armor and HP so that you have a large buffer zone. That way, if your avoidance fails and you get hit 4, 5, 6 times in a row, you won't get destroyed because healers have enough time to react to the drop in HP. I have always been a huge fan of avoidance tanking. In BC, the major issue with avoidance tanking was rage starvation; As a warrior, if you don't get hit, you don't get rage, and thus you don't get threat. EHP guaranteed that you would be hit often enough to retain solid rage levels and thus solid threat. The second issue was spikiness. Even with high levels of avoidance, it's still possible to be hit repeatedly. With EHP, you have a solid buffer for those situations, whereas avoidance tanking requires healers to watch for spikes and get quick heals off.

There's no question whatsoever that you take less damage when avoidance tanking than when EHP tanking. However, healers have no issue right now maintaining high mana levels while pumping huge heals, and thus people consider the HP buffer to be more important than the decrease in damage brought on by avoidance tanking. The proposed changes to healer mana regeneration may be enough to push more people toward avoidance.

It's relatively well known that avoidance scales exponentially with respect to itself. For example, going from 0 avoidance to 10% avoidance is a mere 10% damage reduction. However, going from 70% avoidance to 80% avoidance is a 33% damage reduction. Because of this fact, as your avoidance increases, avoidance becomes a better stat to stack. And because avoidance works as a multiplier on HP, as your HP goes up, avoidance becomes a more powerful stat to stack. Which means in the long run, everyone will be stacking avoidance, eventually. To combat this, and in an attempt to prevent people from reaching the mythical and oft-videod 100% avoidance, Blizzard implemented diminishing returns on avoidance. As your avoidance gets higher, you need more and more rating to add an additional percent. However, there's a serious latent issue with the DR calculation. Diminishing returns on avoidance excludes anything that gives a % value. For example, a talent that adds 5% to dodge does not affect diminishing returns.

The previous three tanking classes were all equal in terms of avoidance from talents. Warriors and Paladins receive 5% each to Dodge and Parry, while Druids receive 10% to dodge (since they are incapable of parrying). However, Death Knights can receive a whopping 22% avoidance that is unaffected by Diminishing Returns; 5% to Dodge from Anticipation, 10% to Parry from Blade Barrier, 3% to boss-miss from Frigid Dreadplate, and an additional 4% Parry from Runeforging.

At low gear levels, say 20% avoidance from gear, this isn't a HUGE deal. If a warrior has 30% avoidance and a DK has 42% avoidance, The DK is taking roughly 17% less damage. This is a number that could easily be made up for via things like the ability to block, the innate damage reduction on Defensive stance, or a number of other factors. However, when we reach the extreme end of avoidance, say 55% from gear, we're in dangerous territory. A warrior at this point would have 65% avoidance, while a DK would have 77% avoidance. The DK would be taking 35% less damage than the warrior. As avoidance available on gear increases, the gap widens even further.

The issue of spikiness can be mitigated two ways. First up is the talent Vampiric Blood, which I still hold is wildly overpowered. The general rule is that an avoidance tank will have significantly lower HP than an EHP tank, and thus has less of a buffer zone. Vampiric Blood allows you to have 15% more HP for 30 seconds out of every minute. My standard high-avoidance set has 27k HP, while my high-HP set has 32k HP (both unbuffed). Vampiric Blood raises the avoidance set to 31k, drastically reducing the difference in buffers.

The second manner in which spikiness is reduced is the talent Will of the Necropolis. WotN can actually be considered to be additional HP, based on your current HP. For example, from 100%, your HP is increased by roughly 17%, as an attack dealing 117% of your HP will be reduced to (117 * .85) = 99.45% of your HP. The vast majority of the time, the talent will act as between half and a third of that value (5-8% effective increase in HP).


So, anyway, the whole point is that DKs can have way more avoidance than other classes due to talents that give us undiminished avoidance. Also, the spikiness issue is reduced by some exceptionally powerful talents. And lastly, DKs suffer no penalty from not being hit, and thus the only meaningful reason NOT to stack avoidance is threat concerns which are, honestly, laughable right now.

To test my theory that avoidance-based DKs are exceptionally powerful, I gathered a few friends to do some testing on Patchwerk. Not a kill, just 6 minutes of 1-tank, 1-healer PW.
Video: YouTube - Patchwerk 10 (High)
Healer was in about half blues ( Armory Link )
Final screenshot of recount showing avoidance levels: http://www.saichotictech.net/WoW/PatchwerkAvoidance.jpg
70% avoidance from regular melee, 73% from Hateful Strikes. As time goes on, it'll only get worse. Either Talents must be added to diminishing returns, or DKs need to have their avoidance talents nerfed significantly. Otherwise, we'll be pushing 100% avoidance with almost no concerns whatsoever come Ulduar.


On a side note, if any boss is ever given the DW attack penalty in WotLK, avoidance tanking will be even more hilariously overpowered.





Comments? Questions? If anyone can show me that this isn't in fact getting ridiculous and that other classes' unique mechanics make up for the lack of additional avoidance talents, I'd love to see it. Also, if anyone of any other class has solo-tanked PW for an extended period, I'd love to see that too. Video of doing this on 25man will be available as soon as the WW server lets me get my damn Immortal title.

Excellent post. I recognized the DK's high innate avoidance as well and have been gearing as an avoidance tank. My Patchwerk parses fall in the 75-80% overall avoidance range (example). Even with diminishing returns, it seems perfectly reasonable to continue to stack avoidance well into the 80's and 90's as a Death Knight, all but eliminating physical damage taken.

Um, I'm not sure there's anything more to say about the avoidance scaling issue now. Just looking at your gear, which is comparable to mine, but combined with your chosen professions of bs/jc pushes the avoidance into the ludicrous numbers as you say. Even my modestly gemmed/enchanted gear has me pushing 65% avoidance in important fights.

My only problem with stacking avoidance has always been that it makes incoming damage unpredictable. Ideally healers won't be waiting for you to get hit to heal you, so in the end even if you are ultimately taking less damage, you aren't receiving any less healing. If the healers do slack off and the big spike comes, thats when things go awry. That said, minimizing incoming damage is definitely the goal of a tank. My philosophy has always been to try and stack EH to where you have enough to soak a few hits and then go all avoidance.

Of course the thought that stacking EH > avoidance is based largely on the idea that doing so sacrifices your other stats, which isn't as true for a DK tank as it has been for other tanks in the past. As you say, the amount of avoidance DK tanks can get is ridiculous. We get tons of avoidance from talents, and we get TONS of EH from frost presence so neither is really an issue as long as you aren't in low level gear. Add in the fact that a DK tank will have some sort of cooldown active most of the time to cover hits that do/would have gone through, and you pretty much have your bases covered without having to look too closely at gear. A DK tank can easily have 65-70% avoidance by accident, just from maintaining 540def.

In general avoidance is a tricky thing just because it is exponential as you say. 22% avoidance talented is obviously a lot, but new tanks need it, and even geared tanks would be pretty crippled without it I think. That 22% makes the difference between barely being able to tank an add on Anub'rekahn or feeling like you could die at any moment in a heroic, and comfortably main tanking bosses without a worry, for me. But of course adding a static amount to a non-linear stat can be problematic, and while I think DK tanks are in a pretty good place right now, it does seem like it could be a bit much come Ulduar.

Not being a full-time tank in Wrath I'm not familiar with how exactly the avoidance DR works or how talents interact with it. I would think that its possible that you may need so much avoidance to get any benefit past a certain point that its not worth stacking, but thats for someone familiar with the formula to say. My thought is that (assuming it isn't already the case) perhaps the static value from talents should be the starting place for the DR formula and all avoidance past that is diminished. That way everyone benefits from the talents equally, but more geared tanks have more DR to face to get the same benefit. I could probably explain that better but I'm not so good at the mathulation.

I agree that it's an issue; because of the raw avoidance bonus over the other tanks, we scale much better with avoidance gear while still scaling nearly as well (druid) or better (warrior / pally) with stamina.

One easy but interesting solution might be to change Blade Barrier. Instead of giving it an effective free 100% uptime, perhaps change it to use a Blood Rune for 5 seconds of +10% parry? Sacrificing threat for survivability could be an interesting option, and it should be reasonably well balanced between the three specs (Blood gets more damage from their BR, but also have more available).

Unbreakable Armour is being changed in 3.1, so it shouldn't be a worry anymore.

Lichborne probably also needs a nerf. With decent gear, it's pretty close to saying "Makes you immune to melee attacks for the duration". Then again, on a 3 minute cooldown perhaps Blizzard isn't too concerned about it.

Excellent post. I almost wanted to call BS on the 70% stuff. but the links were very good.

Do the mobs in naxx have the same buff as sunwell had?

This. And it would have worked, if not for those meddling kids!

I mean, those talents that ignore diminishing returns.



I don't like the idea of making Blade Barrier a clicky ability. DKs have a lot of clickies as is. I feel like if the avoidance runeforges were removed or placed on DR, and Blade Barrier had its Blood Rune requirement removed and was just a flat 5% parry, it'd be more balanced. It'd be a straight nerf, it'd be boring and normal, but it'd be balanced. Right now, it isn't.

I understand the concept. And we are powerful characters but lets not forget that pallies, warriors, and druids get special things too and we need that extra avoidence from our talents to compete with the rest of the tanks .

Warriors and pallies both get shields and actual tanking weapons. So a geared tank has 60%+ avoidence just from dodge parry and block not including miss. Druids don't really have to worry about def and only have to worry about one avoidence tree and have a lot more HP then all the other classes.

Most DK's dont have the ability to use Swordshattering enchant because of the low def on higher level items. So.....

It is easy to hit 540 with 213 gear if you use the Gargoyle rune but you would either have to use [Repelling Charge] or [Seal of the Pantheon] to stay at 540 and use the Swordshattering rune. (excluding the def you can from the icy touch def sigil or roll without one of the DEF trinkets (listed above) and hope the Icy Touch/Def Sigil brings you to 540 and you don't have any down time) Or option C stack def gems and nerf your hp and avoidence.

If you do use one of the DEF trinkets above you then you now lack 1 trinket slot. For, atleast myself, i like having the ability to switch out trinkets. I can stack stm with Eseence and Monarch Crab or i can stack avoidence with Rune of repulsion and Valor or War dodge trinket.


To sum it all up and the point im trying to make is that with warriors pallies and druids ability to tank is very different from ours. I guess we should say we are in a class of our own when it comes to tanking and because of that the WOW gods don't seem to subject us to the same laws as the other tanks. (Another good point to back-up that we are in a class of our own is that we are the only tanking class that doesn't need to be hit to generate or version of "Rage")


When it comes to physical Dmg, imo, all the other classes have a step up on us. When it comes to magic dmg tanking. Then id say there is a unbalance

Interesting writeup. Good job explaining the deathknight stuff for people who aren't familiar with the class. The only problem is this one conclusion:
And I suppose there are many cases where this holds; however, I think stacking health to survive certain combinations (special + auto), particularly those involving at least one magical attack will still be very popular, even if you're reaching over 80% avoidance.

The multiplier argument is also true of armor, although I suppose armor is less of an issue as a deathknight given the frost presence buff bringing you up to (or near?) the cap with raid buffs?

I honestly don't think they'll ever have a DW penalty mob again (due to recent T6/Sunwell bosses), so that's a pretty simple solution to that problem. Eventually they'll have to fix this avoidance problem if it's as bad as you say (actually they have an alternative where they just never give any avoidance beyond what's on current gear, but I don't think that'll happen). The easiest solution is probably to bring deathknights down the talented avoidance levels of warriors and paladins.

My Avoidance with 10/51/10 spec, in combat while fully raid buffed, is 69.9% (including base miss + defense miss).

Why are you calling BS?

From a healer perspective, I have never understood this avoidance scales exponentially point. While yes I understand your example of how the percentage avoided is difference between 70-80% and 10-20% is different, the amount of actual damage reduced is still the exact same.
Say a boss hits for 10k every 2 seconds (5000 dps), and you have 10% avoidance. You avoid 1 hit every 10 swings on average, putting your damage taken at 4.5k dps. You bump your avoidance up to 20% and now take 4000 dps, a 500 dps difference.
Now let us say you have 70% avoidance, you'll be taking 1.5k dps. At 80% you'll be taking 1k dps, still a 500 dps difference.

Maybe this viewpoint is due to me being a druid healer, so healing is more of a how much hps do my hots need to do to cancel out a predicted dps income, so if anyone could point out what I've missed, it would be much appreciated.

Block isn't really avoidance; If a boss hits for 27k and you block 3k of it, that's nowhere near as powerful as if you parry, acting almost like attack never happened.

Druids generally only have more HP than other classes because they stack it exclusively, since they cannot be crit. I can screenshot tanking with 52k HP if you'd like, it just feels exceptionally pointless, and my healers complain that while I have a huge amount of HP, I take a ton of damage. I only keep the set in case there are more things like the back half of 4H (aka Spellcaster Bosses)

Stacking defense gems does not in fact nerf your avoidance. Defense adds a small amount to Dodge, Parry, and Miss. When you combine them together, it's *almost* even when compared point-for-point against Dodge. It's significantly better, point for point, than Parry.


Yes, the tanking classes are all different, but if there's anything showing that the ability to Block or not needing Defense on gear allows similar levels of damage reduction, I'd very much like to see it, and I'll agree completely that the avoidance increase for DKs does not imbalance us.

Sartharion is a good example of this right now; No one in their right mind would stack straight avoidance for Sarth, as you need an HP pool to soak huge breaths. Extremely large spellcasts are the bane of the Avoidance tank.

It's significantly harder to really stack armor given the fact that all items with the same ilvl have the same amount of armor, so pretty much everyone in high-level gear is going to be sitting at about the same amount. I haven't taken a close look at non-multiplied items that give armor (Like cloaks and rings with 400 armor or some such), but i will soon... The other issue is that the DR on armor is very well implemented, and there's no magical nondiminished armor amount you can tack on.

Yeah, I agree with everything here. Adding the DW penalty would bring many players who have gemmed entirely for avoidance up to 100%. Gear has to improve somehow, and having hard cap on the total avoidance allowed via gear is a really nasty boundary for gear designers.


Lets say you're taking 5,000 DPS with your current avoidance, and you need to be taking only 3,000 DPS in order to survive. If you start out with 0% avoidance, you need to increase your avoidance by 40% to decrease it by 2,000. However, if you start out with 90% avoidance, you only need to increase your avoidance by 4% to decrease incoming DPS by 2,000.


While it's true that each percent of avoidance reduces incoming damage taken by a static amount of DPS, the reduction in terms of percentage of current damage increases quickly.

I agree that it might be a concern in the futur, if healer's mana is a problem again.

But right now, it's not; cause like you said, right now the HP buffer is more important. And before it become one, DK will probably be a lot different than now (since our trees and abilities are reworked almost every patch).

But yea, in a hypothetic mana-short fight, DK are superior as of now.

Well, I'm pretty surprised at this.

I had always assumed that they had done the sane thing and diminished returns on avoidance ratings based on your current avoidance, not on your current rating as they appear to have done (in other words, it appears that instead of applying flat modifiers and then diminishing returns on ratings based on current avoidance, it appears they apply the rating, diminish them and then add the flat modifiers) because it would result in precisely the issue we're seeing here.

The solution (to me) seems obvious: when calculating avoidance, convert flat avoidance modifiers to the equivalent rating required to reach that amount of avoidance given by those modifiers AFTER DR. Then add avoidance rating given by gear and diminish the whole thing as a lump sum. Yes, they will have to rebalance ratings after this change, but the current way of doing things is simply unsustainable.

As distasteful as Sunwell Radiance may have been, I dare say it was more of a fix than the diminishing returns on avoidance was. Avoidance inflation is one of the fundamental problems with WoW's game design: to make fights difficult, it forces the developers to create bosses that are increasingly capable of one-shotting a tank, simply to maintain the same average incoming damage on the tank; even if these bosses do not one-shot directly, their hits must, on average, deal a larger and larger percentage of the tanks max HP than bosses of the previous tier of content. Anything else would lessen the burden of healing and effectively make that part of the game easier.

Some might say that this shift in how the game plays is fun or interesting, but I cannot see how that is so in this particular case. Having a small number of fights that put the tank's life at extreme risk is fine, I'm sure. It's diversity in encounter design. Having, in general, all fights trend this way smacks of homogenization in my mind. Homogenization is not fun, and that is the problem with avoidance inflation: it restricts encounter design. Every fight becomes the same spammy healing deal that Ghostcrawler has so vigorously spoken out against in recent days (though the reasons for such would be different--healing can be spammy now because mana is not a constraint; healing would be spammy later because it's the only way to keep up).

I think what we have to come to grips with is that avoidance cannot inflate unchecked without having these effects on encounter design. There has to be a check, and like it or deplore it, Sunwell Radiance was that kind of check. Simple diminishing returns will not fix the inexorable trend: that avoidance only goes up, not down.

This isn't necessarily the case. Diminishing returns, on their own, are a perfectly viable answer assuming two huge sweeping factors.

1) No matter how high your ratings get, you cannot reach 100% avoidance.
2) At a certain point, it becomes more effective survival-wise to stack something OTHER than avoidance.


The first part is problematic in that it actually is reasonable to attain 100% avoidance with another tier of gear. Take a look at the DR formulas (They're somewhere here on the EJ boards...) and note that if you attained around 2/3 of the theoretical "cap" on DR, talents could push you up to 100% avoidance. If talents were added in to DR, then 100% avoidance would become much more difficult, however high avoidance levels would still be an issue. This brings to the front the concept of other stats to stack for survivability.

The only other stats that actually reduce damage taken are Armor (for all classes) and the combination of Block Value and Block Rating (For Warriors and Paladins). Armor stacking is... Strange. It's hard to really find gear that pushes armor value, and there's very solid and well-founded DR on armor. Your best bet for armor stacking is in rings, trinkets, cloak, and neck, and the amount of armor you can actually stack is relatively low. However, I'm definitely going to be looking at how much actual damage mitigation that can net you.

Blocking is significantly more powerful, as it's a static damage reduction from each blocked attack, and if you stack avoidance as a warrior or paladin, it SHOULD be possible to reach a point where any attack that is not avoided is blocked. This makes a very interesting system for those tanks; Avoidance reduces the number of attacks that land, Armor is a %Reduction on each landed attack, and Block is a static reduction on each attack. This provides many unique and roughly equal ways to reduce damage. However, DKs and Druids don't have similar mechanics, we can only work off of Armor. But I think I've started rambling and gotten off topic... My point is, there needs to be a stat, that we can improve, that decreases damage taken, that ISN'T avoidance. Combine that with an inability to be truly unhittable and tank gearing will be interesting.


Also, it's possible to have high overall damage without too dangerous of spiking via more, but smaller, attacks. If you're hit 50 times for 100 damage it's the same as being hit 100 times for 50 damage, but the second scenario will have less burst spiking and more consistent damage over the duration of the fight. However, I feel like Blizzard wants burst-spiking to be the reason not to get high levels of avoidance, and if every boss is hitting you for a small value every quarter-second, there could be some very real issues for server performance. Could be wrong on that last bit, but I doubt performance is an issue that can be ignored entirely.

There are moderate points in your post that I agree with, and then there are several that I also disagree with.

First off, throwing in things like a DK's ability to get 22% post-DR avoidance combined with talents like Will of the Necropolis and Vampiric Blood is a little misleading. It would take a ridiculously awkward spec that could, at most, combine nothing but sheer absolute nothing but survivability at the cost of any real type of threat. The only situation which would currently favor that would be Sartharion, but as you stated in your post, Sartharion isn't really an avoidance tank fight, anyways. Due to a fight like Sartharion (coupled with the Bone Shield nerf), as well, I've stacked Stamina, and can't even use the Swordshattering Rune versus Ebon Gargoyle due to crit.

Additionally, contrary to what is probably popular belief, Death Knights still get hit harder than any other tank. We'll take a Patchwerk parse for instance, going purely from our guild's WWS parses, from being a hateful tank, Druid takes an average hit 16.2k. I take 20.6k - I don't have a Warrior one on hand as we always tend to use our Feral for tanking it most of the time, but I'm 95% certain that they get hit somewhere in between that gap. The reason for this is that is, and you fail to mention, is that Death Knights do gain significantly higher avoidance - but other classes gain significantly higher mitigation. Be it Warriors and Paladins through Block, and all other tanking classes outside of Death Knights gain a flat % damage reduction on top of their armor that causes them to take significantly less damage from pure melee hits that do land on average than Death Knights do.

The statement that "eventually, all tanks will end up stacking avoidance" is something next to impossible to state right now as it depends entirely on the assumption that bosses will be predominately physical damage and not hit ridiculously hard or fast. Using Patchwerk as an example is playing into a situation that one can't even realistically say favors Death Knights - saying you avoided 70-ish% of attacks means absolutely nothing. How hard did you get hit in relation to other tanks? What is the avoidance rate of other tanks? How much damage did you take overall? As you even stated yourself, high magic damage bosses (or bosses with very high potential damage rounds) are the bane of avoidance tanks, and Patchwerk while being nice to show sheer tankability, outside of the years-behind Naxx encounter design, it's the only example of a boss -like- him, the only thing even close being Brutallus, but that's kind of hard to compare too, as it was created pre-DK's and they would dominate that fight because of the way their mechanics work.

You can only start stacking avoidance, as I'm sure is obvious, once you have the hit points to live through the worst case scenario. This does present its own set of problems and another issue, of course, as Death Knights are also capable of achieving the highest HP possible out of any tank (I can hit up around 55k with Vampiric Blood, which is up 50% of the time).

Now, that's not to say I disagree with the entirety of what you've said, though. I do think DK avoidance values are high (I also think their mitigation is low) - but I don't think this results in them being superior tanks. I think what results in them being superior tanks is the cooldowns. If you took our cooldowns away from us, we would be crippled as tanks. Death Knights are, at their core, exceptionally weak tanks, that provide nothing but taking more damage over the long term regardless of their level of avoidance, and not only do they take more damage, but the damage is less predictable (and requires even -more- healing). The problem, though, of course, becomes that we have cooldowns that between everything, we can have -something- up pretty much 100% of the time, that essentially make us greater than. And other tanks don't really get to use their cooldowns proactively, as their cooldowns are too long, or their durations are too short, to do so.

If you take avoidance away from Death Knights, without adding anything else in, I don't think that they will end up being viable as tanks. I do feel the avoidance counteracts the mitigation that Death Knights lack in comparison to other tanks. If we wanted to go on a rant with DK's and the armor cap - which, granted, they still do not hit - we reach the other side of the problem as to why DK's have far inferior mitigation - being that, assuming they ever "do" hit the armor cap, we do not have the additional 6-12%~ damage reduction that other tanks have.

Really, the problem is either other tank's lack of cooldowns, or Death Knight's overabundance of them, and that really comes down to Blizzard deciding one way to go or the other. I won't disagree with you that Death Knights are probably the best tanks when it comes to single target tanking in the majority of situations - but I think you're barking up the wrong tree. Likewise, Death Knights suffer from being inferior AoE tanks (to Warriors and Paladins, at least) though, granted, that's not what's up for discussion here - avoidance getting too high? Maybe, it's hard to say, you really have to get up there to see how punishing that DR gets - it depends entirely on the gear available and itemization.

Also, Blizzard has promised (?) significant DK tanking changes in 3.1, so maybe they're finally going to take DK's off of being avoidance tanks like I was harping on in beta, we'll see.

EDIT: Really though, it would probably be in Blizzard's best interests to even put in an avoidance hard cap of, say, 75%, it might have to cause a change in either talent layout or itemization, but it's probably the best way of doing it versus putting talents in the DR, if you put talents on the DR then you risk the chance of some of them being potentially wasted.

It is balanced.

Warriors get 10% innate damage reduction from defensive stance, plus blocks. Honestly blocks dont mean much and a warrior should always get parry/dodge over blocking stats, but when you add up defensive stance and blocks and all of a warriors talents and compare it to a dk with all of his talents and 75% avoidance (which is pretty much near the cap because DR will definitely kick in at this point and you will not be going past 80), the tanking ability seems about equal. I have 75% avoidance (but it spikes to 80% most of the time) with normal raid buffs in my tanking gear and our healers claim the warrior tank is not any worse to heal than me. Warriors and DK's seem very balanced right now.

I am already pushing the DR cap on avoidance. Im close to 80% and after that I would be dumb to stack avoidance over health. While a warrior can still stack avoidance without worry of the cap and he has 10% damage reduction plus blocks and i dont.

I say diminishing returns are insufficient because on a practical level, you cannot totally eschew gaining avoidance for, say, armor or stamina or block. As I said, avoidance stays the same at best, and in reality, it will go up. There is no doubt in my mind of this.

But because avoidance always increases, we still have the problem: how can Blizzard design a boss that has the same incoming damage "pressure" on the tank when the tank is now avoiding that much more? The answer is obvious--you make the boss hit harder. Faster or bigger hits, either way it forces a subtle change in the way the fight feels: if the hits are strictly bigger (and, bear in mind, this is bigger on top of how much bigger they must be to keep up with HP inflation), then taking any given hit becomes more dangerous, more spiky. If the hits are strictly faster, we have weird effects like charge-type spells getting eaten faster (and thus having less effective uptime), which has significant class balance implications. A combination of the two has a combination of effects.

On the purely conceptual level, it's plainly easy to see that how fights work gets distorted if avoidance is allowed to rise unchecked. If tanks gain more HP and healers can heal for more, then bosses must deal more damage to compensate. But if tanks gain more avoidance, it begs the question of how the bosses are supposed to compensate. Again, if the bosses hit strictly harder, then the worst case scenario (consecutive hits) is more likely to kill you, even if it's less likely to occur. If the bosses hit strictly faster, there are more scenarios where you could die (because, if fast enough, they don't even need to land consecutive hits to kill you), but the higher number of hits balances that out.

Again, in the long run, we can make the strain on healers mathematically equal, but deaths are all about worst-case scenarios.

The two sweeping factors you feel are reasonable really only have subtle effects: limiting avoidance to 100% only limits its scaling to exponential or worse (exponential scaling would never reach 100% avoidance; purely additive avoidance was faster-than-exponential scaling). In the effective HP metric, terms that multiply each other will scale each other according to their trends. Anything slower than exponential increases the value of other stats as that stat is stacked. The current avoidance DR is s.t.e., so it increases the power of stamina, armor, etc. as it avoidance is stacked, but I do believe it is faster than linear. Stamina and armor are linear (block is a nightmare...), which means they DR themselves faster than avoidance does. While I think your second condition holds--at some point, avoidance will DR itself so far that other stats are strictly better--it may well not be until we're at crazy 90+% avoidance and bosses have to hit 4-5 times harder than they might otherwise just to maintain the same healing pressure.

I think Blade Barrier needs to stay like it is, at least in terms of how you keep it up. 10% parry is huge at high levels of avoidance, and for blood and unholy every meaningful AoE threat ability is tied to blood runes. We shouldn't take a ton more damage for holding a blood rune for a few seconds to get a DnD down or to have pestilence ready when adds spawn.

If the problem is 10% parry, then that's what needs to change. Make it mitigation instead of avoidance, or reduce the amount of parry, or put it on diminishing returns. If the buff is too big, then the right solution isn't to leave the buff too big and make us struggle to keep it up.

If you say next tier will give 30% more effective avoidance to you(you have 70% effective avoidance now) can you tell numbers. How much you need defence, dodge or parry rating or some combination of those. How about 90%?

With current DR on avoidance stats, 1000 Def Rating, 1000 Dodge Rating, and 1000 Parry Rating, combined with base agility and a reasonable amount of strength should put a DK tank in the mid 80% avoidance range when including Blade Barrier, Anticipation, and Swordshattering, but not including Frigid Dreadplate (since Blood and Unholy won't typically spec into that).

Not making any particular point, just food for thought.