Keep in mind that as a speculative thread this may all be rendered moot by patch changes or fight mechanics in T16, but that in order to prevent a "Firelands 2.0" style tier it's best to speak early and often.
So! Without further ado, I'll put the big issues - as I see them - facing Blood DKs now and in the future.
Note that these are more in the order that they occur to me, not order of severity.
Problem #1: Our mastery works against itself.
Death Strike is an interesting beast: It's sort of the ancestor of vengeance, in a way, in that it's a defensive ability whose effectiveness scales with how hard we've been hit recently. The problem is that while vengeance had many iterations done to fix its issues, death strike has been left largely alone over the (literal) years.
Simply put, every time we hit with death strike, we get healed based on how much damage (actual damage) we've taken, and then we get an absorb shield based on that heal.
The problem stems from death strike only counting actual damage taken. Let's say I take a large hit, then use my last frost and unholy runes to death strike. I parry the next boss attack, the huge blood shield fully soaks the next hit. Suddenly, the boss winds up a really hard hitting special attack just as my runes refresh again.
I have two choices at this point:
- I can use death strike, but the shield will be pathetically small, because I haven't taken any damage in the last five seconds. I'll take a large hit from the boss special, and then my healers will need to run around in a panic putting health back. Since I'm out of runes, it's entirely on them.
- I can not use death strike. I'll take an even larger burst, because death knights have the lowest passive mitigation of any tank (including monks, factoring in their stagger), and then get a huge blood shield by using death strike. The healers will likely pop a CD when they see my health drop into the floor... if I even survive the special hit in the first place.
Now, let me make something clear: Mastery working against itself isn't inherently a problem, except insofar as it contributes to our second major problem. It can be balanced around. The side effects, however, cannot.
Problem #2: Our mastery makes us take huge spikes.
Thematically, blood is all about taking big hits and healing them back. Personally, I like this. It's a neat mechanic. The problem comes when you start doling out special attacks that get close to a tank's maximum health.
If the difference between a paladin and a death knight is that the paladin takes 10% of her health while the death knight takes 20% and heals 10% back, that's fine.
If the difference between a paladin and a death knight is that the paladin takes 40% of her health while the death knight takes 80% and heals back 40%, there's a very serious problem.
Anyway. Blood shield is a very binary thing: It gives us a static absorb effect. You can actually count it something like a second, guaranteed avoidance: One death strike will mitigation 1-2 full boss autoattacks, depending on how much mastery you have.
The problem is then how we take damage. Healer mana efficiency rewards foresight, in that while healers can put back a lot of health quickly, it costs them an inordinate amount of mana to do so. If a warrior tank drops from 100% to 80% to 60% to 40% in three swings, a healer can cope with the steady damage income and compensate for it. If a death knight doesn't drop for the first two swings, but then plummets to 40%, the healer can't know if the death knight has the runes or not to react to it and is forced to wind up a big expensive heal to put back the same damage suffered by the warrior.
Problem #3: We don't have a good way to soak potentially lethal hits.
This is an extension of the first two, and is a side effect of heroic raid bosses hitting tanks post-armor for over half a million damage. Unless we're stacking stamina - which has its own huge list of problems - we don't have the pool to soak hits that size to get the full benefit from our mastery.
This is, in essence, a problem with having an almost exclusively reactionary mastery: Every other tank has a way to reduce the initial size of a hit. Death Knights, unless we're "pooling" damage taken by intentionally standing in the fire (or not using our active mitigation), don't.
TO BE CONTINUED...