You seem to have misunderstood what I was saying. Immutable gives five seconds of invulnerability. Rock Hard adds another five. Pain Suppression is eight. That gives 18 seconds of invulnerability without needing any form of self healing. Do you disagree with this?
My whole answer about the selfhealing was indeed misunderstood, because i took selfhealing as the whole, including Immutable’s heal and Pain Suppression’s heals.
Based on this (18 seconds invulnerability in a 21 second window), I state that self healing is not very important. I never suggested it should be removed completely. Further your examples show how a missed rotation is lethal, not that self healing is required. The first example is simply failing to chain pain suppression after rock hard, and the second example is failing to overlap pain suppression and twist fate.
My examples are indeed actually bad, that’s what happens when i try to reply to a serious topic while doing scenarios at the same time XD. What i should just have stated is that the extra selfheals coming from Percussive and such “can” save one’s life in case of a screw up in chaining CDs, pretty much. One of my resources even proves that point, from the flappy regional tanking PoV. Since i had very low gear and every hit landed without protection buff was a one shot, in that situation, only perfect cooldown chaining was important. The other important thing to consider is that we can actually go further: the undergearing is possible because of how much of a strong CD coverage we can get, so stats as whole matter actually very little. Stats and extra selfheal sources start to matter once we remove a cooldown or 2 to bring some extras.
So to survive, EHP + self-heal must be bigger than 3*y, where y is incoming damage from the boss. EHP is 2.83 times your normal HP (backlash is 0.55 of HP, twist fate multiplies shield+HP by 1.83). So, if the boss normally hits you for less than 94% of your full HP, you will actually survive the last three seconds without any self healing. Also only self healing gained from the four hits after your last pain suppression heal matters.
I’m not very good at this kind of maths… yet, so i’ll just trust your analysis. We can potentially even add that in case of a screw-up, one can dodge-roll behind the boss, or just run away with Quickness (Alacrity helps big time). Further notice if one happens to derp on CD rotations: running away is possibly the only way to temporize until CDs are up and rolling correctly again.
One last thing to add: many bosses have special cast-based attacks that might one-shot under Thick Skin or Twist Fate + Backlash (things like Searing Brand from HR4 can one-shot even while under Rock Hard depending on stats) while the tank cannot necessarily take an interrupt since for the example of HR4, we are actually used to bring Catastrophe Shelter when we tank. It is possible to ask for an extra interrupt in form of an active ability slot, for sure, but what just works for me personally in this situation is dodge-rolling behind the boss with good timing to stopcast his Searing Brands, OR delaying cooldowns a bit to line up Immutable with Searing Brands, it is possible since the boss does not attack the tank without any break since he has 3 casts (Mine, Molten Metal and Searing Brand) during which he does not autoattack. It is also very easy to do with CD reductions (head signet and/or Efficiency weapon affix).
So my advice to players wanting to try out sustain tanking is to take your rotation seriously. That’s what keeps you alive, not self healing. For new sustain tanks, playing at their appropriate gear level, asking dps to help you with a second gadget is much safer than trying out a three-buff rotation, which is a lot harder and actually relies on self healing.
Yep, exactly what i’ve said above concerning selfhealing with less cooldowns. Again, i’m sorry for the confusion.
Back to the Red Hand Destroyer if you don’t mind: i actually glanced on my logs, and found out that the split of Pulverises and Ground Pounds in terms of hits in single target situation is about 60/40 in favour of Pulverise on tank & spank bosses. If we consider half of the Ground Pounds with 30% extra additive damage from Red Hand (i think this is even an overstatement), it will roughly give an extra of 1.77CP of aggro every 5s. If we compare this to the output of the Frost-Bound hammer, for instance, it will be an average of 0.3 x 0.85 = 0.255 CP/s (0.3CP is the average damage it deals and 0.85 is an arbitrary 15% penalty it gives from not benefitting from Weapon Expertise, i believe this proc does not benefit from it despite usually weapon procs benefitting from it), so we’re at 0.255 x 5 = 1.275CP of damage and aggro, which is 38% lower that the aggro from Red Hand. I consider this being a solid tradeoff considering how the additional mitigation provided by the Frost-Bound is good.