I've been trying to figure out how the new
Blood Draining enchant works with Ardent Defender. In general, I like the idea of a heal that gets auto-triggered at some low amount of health, and generally I don't give much weight to all the arguments about "X is bad because it can push you out of AD". But in this case, it's a heal that actually happens the instant AD turns on.
So, here's some napkin math. Suppose the boss hits for
x damage every time, and suppose when blood reserve gets triggered it heals you for
y. Let's look at the following chain of events:
- You get hit for x damage, which pushes you below the AD threshold.
- You get healed for y by the enchant, which may or may not push you above the AD threshold.
- You get hit again for x damage, which may be reduced 30% by AD if you're still below the threshold.
That first hit leaves you under the AD threshold by an amount between 1 and
x, depending on how much health you had before you got hit. I'm going to treat this as a uniform probability distribution, meaning that it's equally likely you'll end up anywhere between 1 and
x points under the AD trigger.
If you don't have the enchant at all (and assuming no other heals come in), then the next hit deals 0.7
x damage.
If your health after that first hit is more than
y points below the AD trigger (that is, your health is below (35% of total health minus
y), then the heal leaves you with AD still active, so the next hit still deals 0.7
x damage. The chance of this happening is 1-(
y/x), and in this case the overall effect of the enchant on your health is a change of
y (i.e., healed by
y)
If your health after that first hit is less than
y points below the AD trigger, then the Blood Reserve heal pushes you above the AD threshold, so the next hit deals the full
x damage. If the heal hadn't happened, it would have only dealt 0.7x damage, so the net effect of the heal is to change your health by
y - 0.3
x (which may be a net positive or negative number depending on the size of the incoming attacks and the size of the heal). The chance of this happening is y/x.
So, adding up the health changes for each case and weighting by the probability of each happening, the expected health change from this enchant when it triggers is:
(1-y/x)y + (y/x)(y - 0.3x) = y - y*y/x + y*y/x - 0.3y =
0.7y
So, if you get no other healing between the hit that triggers the enchant and AD and the next hit, then the two important facts are:
- On average, the net effect of Blood Reserve is to leave you with a gain in hp of 70% of the amount it heals for.
- If you get unlucky, the net effect is that you'll gain the amount of the heal, but lose 30% of the damage of the next attack due to being pushed out of AD range. The chance of this happening is equal to the amount of the Blood Reserve heal divided by the damage of the incoming hits.
If the incoming hits are smaller than the heal size divided by 0.3, then the enchant never hurts. For a 5-stack of Blood Reserve the average heal is 2k, which means the incoming blows need to be above 6667 damage for the enchant to ever have a chance of harming you. Hence, for AoE tanking and other small-hit situations like Patchwerk, this enchant really has no downside.
For larger hits it become somewhat more questionable. I'd much prefer that it triggered at 30%, but even as it is I'll probably still take it.
[Edit:]
As long as I've still got the bottom post in the thread, two thoughts about the patch:
[Edit 2:] Okay, three thoughts.
1) With the new tanking libram (+blkval when HS is up) you're going to have the option to skip some judgements if you're hit-capped. Skipping every second judgement in a 69 rotation lets you very neatly slip in Exorcism every 18 seconds. Potentially if you have two other paladins covering JoL and JoW and someone covering a slowing effect, you could skip judgements entirely and replace them with a rotation like Exo-AS-Exo-SacredShield.
2) What are people's thoughts on Divine Guardian? I was pretty skeptical of it as a tanking talent at first since a Holy paladin's Sacred Shield is always going to be better even if the prot paladin has the talent and the holy doesn't. But with the new restriction on Sacred Shield to one target, it's less likely that you're going to have a holy paladin SSing you, especially in multi-tank encounters where you're not the MT. The strength boost to SS and Divine Sacrifice both seem kind of meh, but I like the duration increase as a way to make it easier to keep SS up.
3) Regarding the how-many-points-in-SA question, I think that's really going to come down to personal experience more than anything else; it's one of those things that can't really be theorycrafted all that well, circumstances are going to vary enough from one tank to the next that there won't be one "right" answer for everyone, and you're probably not going to know what
your answer is until you've spent some time playing with the new mechanics.
So, the easiest thing to do in my opinion is to start out with 1/2 SA and just leave one talent point in reserve (i.e., unspent) until you get a good chance to evaluate your mana situation in combat. It's not as though your 71st talent point is going to make or break your spec; you can live with one fewer point in Divinity or whatever for a few days.