I dispute this can ever be eliminated without limiting encounter design massively. Doing Yogg with 10 melee vs. 8 is quite noticeable. Impossible with 10? No. As easy? no. Doing Hodir hard mode -- when you first got there -- without a decent complement of people who truly benefit from the buffs? Not happening. Malygos with too much melee when it was new? Again, nowhere near as straightforward.

Sure, there are fights were class comp is going to make no difference. Flame Leviathan is the overwrought example. Easy fights like Jaraxxus, whatever you have will work. But fight design inherently is going to slightly favor one class or broad type of player. Yeah you want resto druids for Anub. But you wanted one for Hodir too. And Sarth 3d. My guild flat out couldn't do Mimiron at first without 3 healing priests.

But c'mon. 4 paladins are easier than 2, fine. Did you catch the parts about dispersion, vanish, deterrence (?), pain suppresion, etc. Therer are multiple ways to skin the cat. Let's not compare this to Yogg 0 without FoK spamming (pre nerfs). It's not the same thing. Oh, and any spec of paladin can cast HoP.

It appears a few 25 hard modes (and in cases 10man, e.g. Hodir HM with low gear benefiting by ranged) are made by a group of designers with the belief 25-man guilds are comprised of 25 + 10-20 standbies of the same ilevel (and of a distribution of classes) able to be replacements for the (specific needs of an) encounter. This is not overly unrealistic since any strong guild will require several standbies. Now whether a (strong) guild that only has 3-4 standbies is in the minority is another question since they will be hit most.

Due to failures on the parts of our kiters or paladins we've seen that its definitely doable with 2 paladins and thats not too unreasonable to require for the raid. The fact block tanks are SOO much superior than non-block tanks does seem to go a bit against the blizz philosophy of each tank being able to tank the encounter. I'd wager its nearly impossible (if not flat out impossible) for a non-block tank to tank all 4 adds like a warrior can. The fact that the warrior block set is also a weird mesh of lower level gear is fairly counter-intuitive as well (Im not sure what the pally set is like).

The fight, currently, is fairly dependent on numerous factors in raid make-up. This is really no different than many other encounters when they were first released. The issue here is a lot of the raid make-up problems don't get lessened as you've increased in gear because its class abilities that are needed not just class roles (e.g., melee vs range on Yogg or Hodir).

Requiring 9 melee exactly for a fight is not ideal but surely most guilds have some spares so they can change the setup a bit. You are splitting the largest group - DPSers - into 2 groups. Guilds have been distinguishing between recruiting ranged and melee for a long time so it's a balance that guilds tend to have. Requiring 3-4 of a specific class is much more demanding. Requiring specific tank classes more so.
Saying you can mitigate it with dispersion etc is nice but this is a random ability. Say you're going for 50 attempts left, would you risk it all hoping Anub will choose the right classes (almost wrote players there)? No, you'll get some pally alt or wait for another day.

I should've been clearer on that specific class abilities being significantly & noticeably more helpful to the fight then just the class alone. It's clear that due to the high AoE dps requirement of Anub'Arak, stacking melee cleave especially DKs, Warriors and the like, can help quite a bit on the fight. But those "aoe" roles can be filled by quite a number of classes and the AoE requirements get alot looser with more gear.

However abilities such as HoP, are not replaceable through gear or any other class, and it's not a case where you only need one of that class (eg. shaman bloodlust) for it. If you're a guild going for Tribute 45/50 (which most guilds who can down anub are), you're gonna want to have four Paladins just for that security.

As the poster above said, I don't believe guilds aiming for 50 or at least 45 attempts, will resort to far riskier methods of dispersion, vanish, fade, pain suppression, gs etc.

Raid Roles (melee aoe, high single target, range dps etc) vs Specific class abilities (BoP, pre-nerf FoK), are two very separate matters.

Perhaps this problem is really exacerbated by the Anub'Arak encounter, as a result of the Tribute system, forcing guilds to go for maximum optimization and security.

Edit: For clarification, my guild ran on 2-3 paladins for our first week of attempts, and I agree it is do-able, just alot more riskier. We killed anub on our 3rd week of attempts, and we included 4 paladins halfway during the 2nd week, the use of 4 HoPs really made P2 a total breeze.

Another thing to note, if your guilds is really really low on apt paladins, you could run 2-3 paladins , and use a 2 tank strategy as you'll only need 1 frost patch. This allows u to burst up to 5 frost patches, 2 on the 2nd p2, and 3 on the 2nd phase 2.
To be fair, I'm not saying it's impossible with less paladins , but the fact is due to the nature of the tribute system and P2, having more really makes it significantly safer/smoother.

If you don't have access to a block tank, don't use a block tank. The alternative (2 OT strat) is much simpler to perform than not having a Blood DK on HM Vezax or a DK/Druid on Sarth3D many months ago. Both fights were arguably impossible to complete without those specific tanks. Anub'arak is nowhere near impossible without a block tank.

Is it good design? No. It wasn't then and it isn't now.

We found our 2 tank strat to be more sustainable with 2x unhittable tanks. Obviously, the multipliers aren't as nasty, but it's still a much lower HP pool for leeching swarm, and a lot less damage taken. We tried it several times with both tanks in normal geae, but either they'd die, people would die to PC, or we'd miss the enrage.

In any event, a block tank is invaluable, even in a 2 tank strat.

Pain Suppression, Guardian Spirit, Hand of Sacrifice and Imp. LoH aren't random abilities, though.

And the fact about Dispersion wasn't just Dispersion; it just happens to be an example but, all Priests, Druids, Warriors, Death Knights, Paladins and some specs of the other classes all have some sort of cooldown. That is, more than half the classes possess something, and for the others that don't you can use one of the above 4 or HoP.

GS won't help since it only prevents one killing blow. Imp LoH is merely 20% less damage taken, so it's hardly enough.
Not sure what can Druids or DKs do - IBF is fairly weak unless you have defense gear, barkskin is always weak.
I'd say the main gripe with Anub is that you need both those HoPs and specific tank classes, therefore severely restricting your setup.
Not using a block tank is ... not recommended. A DK will take 5-10 times the damage from the adds compared to a warrior/paladin with block gear. This is not an exaggeration, that's the way the numbers work out.

And? It's not like your healers have anything better to do.

Oh noes, your Moonkin gets pursued and you don't have a HoP up. Druid pops Barkskin, your Holy Priest pops Guardian Spirit, your Holy Paladin, Holy Priest and Resto Druid start throwing heals on the Moonkin.

It get's done.

Impale will hit for 15K with barkskin, every second is it, or maybe more? 2 hits without a heal means a dead boomkin and a soon to be very dead raid.
Doable? Yes. Risky and mitigated by gimmicks? Yes. Same can be said for add tanking, although that's not really doable the hard way.
It's a shame that such a fun fight suffers from these class balance issues (again, mostly regarding tanking).

Your numbers seem off. With one tank at 50k removed from the raid, you're looking at 50000*0.3= 15000 hp leeched every second, which gets reduced to 7500 DPS (hp/second) due to the healing debuff which should be present on Anub.

The mechanic behind it is clear, and it is a definite plus for this strat, but I'm not sure how you come up with 20000 and 15000 resp.
It's basically one free DPS slot, and additionally you can take one more DPS to the raid, so added together it may be in the range of 15000 DPS, but not from reduced healing alone.

I suggest you check your logs. Also, it's been proven Anub'arak actually modifies the leech when it heals him. Further, certain talents (which really only affects Paladins) will increase the heal as well.

The damage done by the Leech is taken, modified by Leeching Swarm - Spell - World of Warcraft then modified by MS effects. Your forgetting the middle bit. Last time I checked it was 260% for H-25, but several said it was recently hotfixed to 230%.

The difference between taking a single 50 000 hp tank, and taking an extra DPS instead in a lower tank strat - is actually closer to about 3 dps spots. (2 'free dps' for the less healing Anub'arak gets, and 1 'free dps' that attacks Anub'arak instead of having to tank and attack adds).

The extra DPS that 'only 1' freed up slot that a 2-tank strat allows, is higher than people might first expect: because of Leeching Swarm mechanics and the high STA values in WOTLK for tanks.

Crudely speaking, Anub'araks Leeching Swarm does about ~40 000 dps in phase 3 (2 tank strat), and thus heals for ~45 000 - 50 000 HPS, or a bit under half of your single target RDPS. During AOE phases (my guild at least) you do about 250 000 DPS which can be crudely said to be 50 000 AOE RDPS to 5 targets (4 adds and Anub'arak). Thus during Phase 3 Anub'araks health won't change (Or change very slowly) in AOE phases, only the single-target zerg phases between adds. There's a few assumptions thrown in there, but the general idea is that Leeching Swarm heals for ~40% of your total single target RDPS in phase 3 with 2 tanks, and he'll heal for about 70k HPS in 3 tank strats (about 60% of single target RDPS)

I assume single target RDPS for a raid is 110k, which should be a good ballpark figure. Anub'arak thus gets lots of extra healing via the Leeching Swarm in phase 3 in a 3 tank strat. I'm not trying to point out 'which strats is better', because guilds can make up their own minds about that - but point out a major difference between them..

The 'just one extra spot' another tank takes up, means alot more than it might seem at first glance.

I would take another healer, rather than a dps, to stabilize the PC healing and make it less prone to failure. Changing from 3 healers for 3 tanks + 3 healers for 5 PC to 2 healers for 2 tanks and 5 healers for 5 PC seems like a big plus in survival for the group.
We use the three tank strategy and have to call a dps-stop before 30% to let those debuff stacks tick off. We still kill him with >1min left on the timer.
If we fail to get the 50 or 45 tries left achievement next week i want to try out the 2 tank strategy and see if it is possible for us to get him down to 30% in one burrow phase. Currently, with adds dying only few seconds before new adds arrive, he is at ~39% when submerging the second time.

I stand corrected, thank you for explaining that.
Now however, could anyone point me to the location where the Leeching Swarm mechanic was discussed? I cannot seem to find it, at least not in this forum (that or I simply suck at searching).

Isn't the first Paladins HoP up before the third Impale in the second downphase? Two Paladins should work fine.

You can use 2 HoPs on the first phase, and none on the last phase, assuming you only need 1 patch to tank the spiders on (My guild managed to do this easily during learning attempts).

I'm not debating whether it is intended or not, but how is this supposed a glitch/technical error?
The adds apply a debuff *on the* tank that multiplies the damage taken by a fixed value (up to 2.25).
Block acts *before* the damage taken is calculated. As such block is very useful (effectively it gets multiplied itself by the mob buff). But it is *not* calculated in error.

If the mechanic on the other hand would have been that the adds apply a buff on themselves, then block value would be deducted *after* the scaling has occured. But this would be an entire different mechanic: A healer or DD getting aggro from an add now and getting hit one or two times is not of real consequence (unless deep in phase 3). If it was a buff on the adds all of these would be one or two hits early on.

Not saying that this is intended or fair to non blocking tanking classes or whatever. Just stating that the mechanic as such is consistent and not a glitch or a technical error.

@Tyrian: I know that the 1 OT strat is all about preemptively stunning/silencing(?) the adds. Nevertheless the execution is dependant on a good knowledge when the shadowstrike signal is going to come. Doing it with 2 OTs does not make you need to know that. Stunning reactively is good enough there. And the second OT is nowhere near 50K HP but way lower (if using block tanks). You do lose DPS, but good planning more than makes up for this. We struggeld with the berserk timer first, but after thoroughly analysing the heals (on Anub and the raid) we *greatly* increased the effective damage in phase3. Our fastest kill was 8:13, and this was with 7 healers and 3 tanks. Leeching swarm effectively redirects and amplifies any heal to the raid to Anub, as such any unneeded heal saved is increasing the effective DPS on Anub.

Do you have a link to the 8:13 kill with 7 healers / 3 tanks. Thats impressive, i'd like to have a look into it.

The notion of Block Tanking as a glitch/unintended seems a bit far-fetched. The adds seem almost cater-made to be done with (the option of) a Block Tank, they even tweaked them slightly a few weeks ago and didn't attempt to stomp out the technique. Whether Blizzard likes the current Block Tank situation and will change it in future is one thing - but it seems an encounter was designed to specifically make good use of them in their current incarnation, at least.

If it's not intended - as you put it - it's a glitch.
A reasonable implementation would be the apply block after the debuff multiplier. The current implementation is non intuitive, blocks (had to use it) 2 classes from being able to tank here, and makes tanks use obsolete gear.
As to why this wasn't fixed - my guess is they felt it was too late. Changing the way the debuff and block interacts would have been seen as unfair at that point.
Perhaps they didn't anticipate tanks going for the extreme block gear, and in their tests block tanks were better but not tons better.

As far as I know, all debuffs in the game work this way (applied last).

The only sensible reason I can think to keep it a debuff is so you can't possibly solo tank the normal, and eventually heroic with gear, versions of the fight. You could easily do it now, if it didn't make anub hit you for 40-50k.