You're missing the point. This would be a valid suggestion if there wasn't a EH problem. There is an EH problem, and that's the crux of this discussion. Provided we live through the spike, the incoming BS has us more competitive, just like last tier. We can't live through that spike as it stands.

BS as a block mechanic works with a condition: you have to get hit, to prevent getting hit later. If you die while setting up the condition, it doesn't matter if the subsequent BS would mitigate 100k.

No, that's absolutely correct. Even against a paladin if you want to take my damage taken and reduce it by the amount of healing and blood shield I did, I often times was only taking about 60-70% of the damage my paladin was (as far as my healers were concerned). Again, as said, your healing, and consequently your blood shield, do not matter at all if a) you don't have a chance to use them before you spike to dead, or b) you are forced to use DS so frequently you run out of the runes to use and die while waiting for a rune cooldown.

You could do the trolololol response and say 'well use a cooldown every time you have no runes for DS', but this happens a minimum of once every 20 seconds, and at most once every minute (refreshing tank cooldowns). Unfortunately this only leaves us with a total of 3 cooldowns to rotate around within a reasonable time frame. 1) Bone Shield (which I assume most dks have learned to use at the same time as IT/PS application every minute), 2) Vampiric Blood (solid choice, 1 minute cooldown, typically works well when you run out of DSes - but also one of our stronger cooldowns we frequently have to sit on at various stages of a fight that shouldn't be used in this scenario and it doesn't actually reduce the damage you're taking so you're still susceptible to spikes), and 3) AMS (nearly worthless if the fight doesn't have substantial elemental damage). You're still going to end up with dead space where you are risking your survival without consistently getting externals rotated on you. A burdensome objective that no other tank has to have.

The fact is that we need to have higher passive reduction and reduce the effectiveness of our shield to compensate. That's all that really needs to be said. Until Blizzard finally does this we have to find a temporary solution, which kind of works with the spreadsheet from pwnwear (which was already pointed out to have it's flaws).

We can 1) go heavy avoidance, risk the RNG, not have any substantial on demand coverage from DS/BS, 2) stack stamina - increase the threshold necessary to kill us, but even doing this will only net a ~13-15k health difference for most gear setups, or 3) we go for a very heavy mastery setup with a major emphasis on hit/exp, and possibly haste to reduce rune regen which allows us to land our DSes when we need them, but falls prey to all the current concerns of DKs (arguably to an even greater degree because you're sacrificing your avoidance often to the tune of ~5-6% or more).

I think I may end up swapping back to a heavy stamina setup with a major emphasis on avoidance, because it appears to be the best route available to deal with the current damage in this tier.

I use the TTL as a very general statement of this was the original thinking of our survivability going back to the original question of when do we go for more stamina over mastery. Regardless of how you put it the fact is that you don't have enough health to take a hit if it goes through, To take the RNG out of it you need more health. I don't know what you run but your situation where you take a 160.1k hit with 48k of tear then you have to be able to take a hit of 208.1k. How much breathing room do you want from this? I'd say 12k isn't enough but that's what I'd get right now. Regem to get that extra 13-15k and you have 25-27k. It's do-able. I'm not trying to troll or tell you that you are doing it wrong but instead of having a convo where we say the class is broken I'd rather find solutions.

We really can't do anything about the class being bad in comparison on some situations other than try to work past it and hope that in future patches blizzard takes this into account.

edit: you must forgive my thinking sometimes I often go back to early posts and respond in that convo while trying to deal with more recent ones as I pull everything together in my head. My thinking is that as a mechanic (DS) it works in comparison, from a taking a hit stand point it doesn't because of mitigation issues and that's evident by dk tanks getting gibbed. As a currently mitigation stand point and reducing damage taken obviously mastery will always be better than stam but reaching the point where you can't possibly be gibbed is more important than reducing damage taken over the course of a fight.

edit2: I took everything back a step and went to the "traditional" gemming and use of sword shattering. With flask, fort and kings I ended with 216k health, 22.70 mastery. Using a situations where stamina >>>mastery where all but maybe 2 or 3 sockets were stamina I ended with 228.9k using scales and moonwell phial trinkets for the stam, stoneskin gargoyle and changed my boot enchant to earthen vitality. I ended with 228.9k hp at the expensive of 1.756 mastery which is a 10.975 DS heal conversion and 4% parry (which we know having more parry means less damage taken and small blood shields). Given a 50k average damage taken you lose 5.5k from the bubble but gain almost 13k hp. Obviously as boss dps goes up then this will be much different and mastery will take over again. This doesn't take into account the successive DS which will obviously be better in the long run for reducing damage taken but given a snap shot in time where you can be one shot this seems very viable without losing too much in the means of longevity. Also you gain about 949 armor.

Given this situation where you take the full on hit and unmitigated tears you get left with 20817 hp. It's low but you are alive.

At this stage it should be fairly obvious that stamina is the most reliable way to deal with Firelands 25 and heroic encounters.

The bosses hit hard enough, that our EH is being challenged before death strikes can occur. So we need to increase our EH to a level that guarantees us a death strike.

The main reasons we stepped away from stamina in favor of mastery were:

• We don't need a larger healthpool. The original Cata bosses did not possess the ability to challenge tank health, outside of telegraphed mechanics. Increasing health did not provide any sizeable advantages.
  
• Healers are short on mana. If we're not carefull with the damage we take, our healers will be oom before the encounter is completed. Overall damage must be minimized to ensure mana conservation. Mastery allows you to reliably reduce damage taken, thus saving mana.

With the current state of affairs in Firelands, neither of these are true.

Clearly bosses are capable or 3-shotting a death knight tank. They present a serious challenge to our EH, since it's possible to die in 6~ seconds. With only 6 seconds, it's possible to eat 3 melee attacks before a death strike becomes avaliable. If you die before you can death strike, mastery has done nothing for you. Also increasing your health pool still improves the effects of many death knight abilites. AMS, Death Pact, Rune Tap, and Vampiric Blood all directly scale with health.

Healers are no longer in starting equipment, clinging to every last drop of mana. They're gained higher itemized gear, with more base intellect and spirit. Even chain casting, it's unlikely that they will run oom before your typical boss fight ends. So long as they're properly utilizing mana regen mechanics, they end many fights with mana to spare.

At the moument I see no drawbacks to stamina gearing in Firelands, but plenty of benefits. We have the highest stamina multiplier of all the tanks, and should use it to our advantage.

So re-reading the ability as blizzard gives it to us

Arcing Slash - "Shannox inflictes 125% of normal melee damage in a 120 degree cone up to 10 yards in front of him and inflicted Jagged Tear on his CURRENT TARGET"

Jagged Tear - "Shannox's Arcing Slash leaves a Jagged Tear that inflicted 4000 Physical damage ever 3 secs for 30 seconds. This effect stacks."

Has anyone tried or can confirm that the damage from Arcing Slash is split among targets and not a flat damage inflicted to every target in front of them.

I found a WoL (World of Logs - Real Time Raid Analysis) where 2 people are getting hit by this ability and are taking 150-160k on that hit but the last 2 paladins there are taking only 115-116k and are actually being hit at the same time. In theory you could have the melee stack on the tank for the higher stacks of Jagged Tear if you find that the extra stamina isn't increasing your survivability. Also looking through log Arcing Slash doesn't seem to be dodged or parried from what I've seen but it can be absorbed so avoidance is really only going to help for the melee hit,

I know this is a crappy idea in general specially moving into sub 30% and is more of a last resort idea but given the fact that DK tanks are having a hard time taking the combo this in theory seems like a viable alternative.

edit: For clarification:
Tank - Darus - 77k hit
DPS -
Cunami - Solo - 168k
Veilira - Solo - 153k
Tearyzo - With Tjokeh - 117k
Tjokeh - with Tearyzo - 115k

It doesn't soak on multiple targets. I have multiple logs from our first progression where I can show Arcing hitting 120-150k+ on both me and a paladin because we were having trouble surviving the melee/jagged tear/arcing slash burst on shannox who was 30/30 (with a paladin tank, I was on riplimb).

The discussion at hand isn't just Shannox by the way, and it appears people are getting stuck on the Shannox situation. It's simply an example detailing the specific damage intake difference between us and other tanks. You could pull similar stats from Beth'tilac, Alysrazor Hatchlings, Baleroc (but this is largely w/e because no guild I'm aware of single tanks Baleroc H with a DK), and Majordomo (see Baleroc parenthesis). I haven't seen Ragnaros Heroic yet, but I know on Normal he hits for shit because the only real spike you can get is a trap explosion with a melee swing without a blood shield or AMS up, and even then it's not life threatening (something around like 130-150k).

I realizes it's not just shannox I just noticed that as a possible way to deal with the potential hit if the extra stamina is not quite enough for this particular situation but as you pointed out it doesn't soak so that's out. I don't have 25 logs since I don't do them it was just something I noticed while looking over some of the parses. I guess it's back to the drawer board so to speak honestly just trying to find a better ways to deal with that particular situation on a whole without telling people to have the DK not be on shannox or avoid other similar situations and in essence telling people to reroll.

That looks like what I more or less came up with the other day when I was messing around with my gems/gear. Go to Stoneskin Gargoyle, Reforge for mastery like we have been doing outside of working for more expertise as needed.

Blue = [Solid Ocean Sapphire]
Yellow stays as is = [Puissant Dream Emerald]
Red = [Guardian's Demonseye] if you need expertise otherwise [Defender's Demonseye]

There is some other enchant changes as well that I noticed looking back at yours.
Gloves: [Heavy Savage Armor Kit]
Feet: [Enchant Boots - Earthen Vitality]
Bracers: [Formula: Enchant Bracer - Major Stamina]

Was curious if the changes are on the bases of maximizing all sources of stamina or if you used a specific weight for each?

It would also push Leatherworking quite a bit higher on the list of professions, because there's still no Bracer - Stamina enchant in cata.

But going for more stamina is only a temporary fix. Assuming bosses hit even harder with 4.3 We'd get into even more trouble, without having the option to regem for stamina, while the other three tanks still have that option.

And a short note on the OP; With the hotfix to DS, wouldn't the GoDS have a higher threat/DPS value than RS? They all were fairly close together even before.
old Cataclysm DK endgame tanking [4.x]

This is a very valid point, what this last bit of discussion has done, effectively, is debated the validity of slightly less effective mitigation in lieu of surviving the EH issue, which needs to be elliminated with class changes. We'll only run into the same problem later on when boss hits get even bigger, and once all the loose stats have been swapped from MST to STA there's not that much leeway left.

We need the EH issue addressed, no doubt, but until that happens sta-gearing for 25man HC seems to be inevitable in the search for survivability.

For that example, it was enchanted under the assumption that "As long as you cannot survive 3 melee hits, stamina > all other stats".

I used [Heavy Savage Armor Kit], [Formula: Enchant Bracer - Major Stamina], and[Enchant Boots - Earthen Vitality] on my usual stamina gear to support that idea.

What I usually run with, are stat weights that say "Well itemized stamina is top priority. Mastery is a close second after stamina. Expertise soft cap is more important than avoidance. Once you have a fair amount of avoidance and dr picks up, start reforging into hit."

Set up in Mr.Robot's optimizer, it looks like this: Stamina Gearing (with hit and expertise)