I've had two kinda vague concepts in mind as I've both healed and tanked in WoW: 1) Maximizing healing on a tank; 2) Maximizing a tank's effective health.
The first started as a healing gut feeling, which is a tendency to favor increasing the rate of healing that the tank is receiving. This is not the same as saying "If I heal more, the tank dies less." It's not that simple, of course. My point is that I would (for example, as a Disc Priest in Cata) favor keeping a Renew active on a tank rather than save that GCD for anything other than a PW:S or a fresh PoM. Popular wisdom was then that Disc Priests did not use Renew, but I did and I think it's because it was effective at topping off the tank, bringing the tank up if not topped off, or preventing tank death with it's steady ticks. It was a versatile and reliable ability.
To support this gut-feeling based concept, I ask what is the ultimate HoT? I think it is the healer them self. A steady supply of Greater Heals is effectively the same in concept as a Renew. Simply put, the difference is the size and pace of the tick, that is all. For this reason, I look towards what maths out the best, never mind what a class/spec is "supposed to use." It's not a question of style to me, but rather a practical assessment of what keeps the tank alive.
The second concept I became more attuned to as a tank, particularly by treating a Blood Shield as an extra health bar on my DK. Again, simply put, effective health is the amount of damage a tank can receive without dying. Increasing that amount leads to less death, particularly during vulnerable moments.
Between the two, my goal has always been to reduce the rate of tank death during progression. With this in mind, my intent is to consider each individual factor that leads to tank death, assign it a value, and deduce the factors into manageable "chunks" of factors. The two chunks I am attempting to quantify are are the two concepts I described, which are preventing death due to lack of heals within a set amount of time, or due to spike damage.
The first started as a healing gut feeling, which is a tendency to favor increasing the rate of healing that the tank is receiving. This is not the same as saying "If I heal more, the tank dies less." It's not that simple, of course. My point is that I would (for example, as a Disc Priest in Cata) favor keeping a Renew active on a tank rather than save that GCD for anything other than a PW:S or a fresh PoM. Popular wisdom was then that Disc Priests did not use Renew, but I did and I think it's because it was effective at topping off the tank, bringing the tank up if not topped off, or preventing tank death with it's steady ticks. It was a versatile and reliable ability.
To support this gut-feeling based concept, I ask what is the ultimate HoT? I think it is the healer them self. A steady supply of Greater Heals is effectively the same in concept as a Renew. Simply put, the difference is the size and pace of the tick, that is all. For this reason, I look towards what maths out the best, never mind what a class/spec is "supposed to use." It's not a question of style to me, but rather a practical assessment of what keeps the tank alive.
The second concept I became more attuned to as a tank, particularly by treating a Blood Shield as an extra health bar on my DK. Again, simply put, effective health is the amount of damage a tank can receive without dying. Increasing that amount leads to less death, particularly during vulnerable moments.
Between the two, my goal has always been to reduce the rate of tank death during progression. With this in mind, my intent is to consider each individual factor that leads to tank death, assign it a value, and deduce the factors into manageable "chunks" of factors. The two chunks I am attempting to quantify are are the two concepts I described, which are preventing death due to lack of heals within a set amount of time, or due to spike damage.
RD = the rate of damage received by the tank, after mitigation
RH = the rate of healing received by the tank from all sources
ERH = effective rate of healing, RD+RH
Th = the tank's current health
Ha = healing from absorbs
ETh = effective tank health, Th+Ha+RD
td = time until death, [ERH]/Th, when ERH is negative (brackets denote absolute value)
Chunk factor 1 is ERH and chunk factor 2 is ETh. In both cases, the lower the number, the higher risk of tank death. More precisely, tank death is a result of either a negative ETh at any time, or a negative ERH remaining in place for the duration of it's related td.
ERH is one of the more commonly assessed factors of tank death. Having a negative ERH can be described as either taking damage too fast and/or not getting enough healing. Whether the blame lies on the tank or the healers (or both) depends on assessing the whether the tank used active mitigation (AM) and cooldowns properly vs. whether the healers were putting out the necessary hps. This might seem somewhat subjective, and tending towards being the healer's responsibility, but a tank would be wise to maximize their abilities in this regard.
ERH can be controlled by modifying two other factors (using some Paladin abilities as examples):
RD is modified by using AM and cooldowns (SotR, DP) and gear (armor, mastery).
RH is modified by using healing abilities (EF, SoI) and gear (haste).
(note, mastery and haste are mutually supporting for Pallys. This is just for example.)
ETh is a factor less commonly assessed. Having a negative ETh can be described as taking too big of a hit or just plain not having enough health. Other than absorbs, this chunk is largely the responsibility of tanks through the proper use of major cooldowns.
RH = the rate of healing received by the tank from all sources
ERH = effective rate of healing, RD+RH
Th = the tank's current health
Ha = healing from absorbs
ETh = effective tank health, Th+Ha+RD
td = time until death, [ERH]/Th, when ERH is negative (brackets denote absolute value)
Chunk factor 1 is ERH and chunk factor 2 is ETh. In both cases, the lower the number, the higher risk of tank death. More precisely, tank death is a result of either a negative ETh at any time, or a negative ERH remaining in place for the duration of it's related td.
ERH is one of the more commonly assessed factors of tank death. Having a negative ERH can be described as either taking damage too fast and/or not getting enough healing. Whether the blame lies on the tank or the healers (or both) depends on assessing the whether the tank used active mitigation (AM) and cooldowns properly vs. whether the healers were putting out the necessary hps. This might seem somewhat subjective, and tending towards being the healer's responsibility, but a tank would be wise to maximize their abilities in this regard.
ERH can be controlled by modifying two other factors (using some Paladin abilities as examples):
RD is modified by using AM and cooldowns (SotR, DP) and gear (armor, mastery).
RH is modified by using healing abilities (EF, SoI) and gear (haste).
(note, mastery and haste are mutually supporting for Pallys. This is just for example.)
ETh is a factor less commonly assessed. Having a negative ETh can be described as taking too big of a hit or just plain not having enough health. Other than absorbs, this chunk is largely the responsibility of tanks through the proper use of major cooldowns.
ETh can also be controlled by modifying other factors:
RD as above.
Ha is modified by certain healing abilities (SS) along with other absorb healing.
Th is modified by using health cooldowns (Fortitude of the Zandalari) and gear (stamina).
Example A.
Tank has 1,000h, and is receiving -100hps as damage and 100hps from non-absorb healing, 50hps from absorb healing. The tank's effective rate of healing (ERH) is 50hps with an ETh of 950h. Time until death (td) is irrelevant, since ERH is positive. In this example, the tank is not at all likely to die.
Example B.
Tank has 1,000h, and is receiving -200hps as damage and 100hps from non-absorb healing. The tank's ERH is -100hps with an ETh of 800h, and td is 10s. In this example, the tank is most likely to die due to low healing.
Example C.
Tank has 1,000h, and is receiving -800hps as damage and 700hps from
non-absorb healing, 200hps from absorb healing. The tank's ERH is 100hps
with an ETh of 400h. Again, td is irrelevant since ERH is positive. In this example, the tank is most likely to die due to spike damage.