This is question that’s asked a lot in the blood DK community, and for good reason. Many high end players stack multistrike, and it is our boosted stat as blood, so why do so many stat rankings show it at the bottom for survival?
Well, for one it IS our best secondary stat in terms of damage output, no questions. But at the same time it’s our WORST stat for mitigation/survival. How can our attuned stat be the worst for survival?
Well, pretty easily actually. Let’s take a look.
Get it? Multi-strike? okay…..
How Multistrike works
Much like crit, it’s an extra chance for damage whenever you deal damage. Instead of just increasing the damage like crit however, it casts 1 or 2 additional spells for 30% the damage of the original. The difference between MS and crit is that MS has 2 chances of giving value, as opposed to crit’s “all or nothing” approach. This is supposed to give MS a smoother feel compared to crit, and in that regard I suppose it succeeds.
Here’s the breakdown:
1. you deal damage
2. you get a chance equal to your multistrike % to get another hit equal to 30% of the original damage
3. you get another chance, completely independent of the first one, equal to your multistrike % to get another hit equal to 30% of the original damage
4. nothing else happens, because multistrike can not proc off multistrikes.
This means you can get 1, or 2 procs on a single hit. Because they are independent, the math behind finding the odds for each outcome is pretty simple. It’s no different than weighted dice rolls, for those of you who took any high school level statistics.
(the chance to roll no procs) + (the chance get exactly 1 proc) + (the chance to get 2 procs) = 1
(1-n)²+2*(1-n)*n+n² = 1, where n = your current MS %.
So just to put this into context let’s say you had 25% MS chance total. The chance to get exactly 1 proc is 2*(1-.25)*.25 = 37.5% and the chance to get both procs is .25² = 6.25%.
To get this into terms of multistrike rating, simply make n = ((multistrike rating)/66+15)/100 to get your raid buffed multistrike %. So the final forms look like:
chance to get exactly 1 proc = 2*(1-(((multistrike rating)/66+15)/100))*((multistrike rating)/66+15)/100
chance to get exactly 2 procs = (((multistrike rating)/66+15)/100)²
Looking at total value
So now that we’ve established how MS works mechanically, we need to put it into context for how it benefits us when we do get a proc. Well for one it gives us more damage, like it does for everyone. For blood, it also gives us 15 RP every time we get a MS proc from melee attacks, which gets used on Death Coil for more damage, t60 charges, and a bit of extra health through Shadow of Death. We’re just looking at the survival portion, so we’re looking at t60 charges and the +hp.
Extra t60 procs from Multistrike
First we need to find how many auto-attacks per minute we are getting (remember, we only get RP from auto attack multistrikes). Your swing speed is determined by your weapon (which will always be at 3.6 seconds for blood due to 2h normalization) and your haste with the following formula:
Melee interval = Weapon Speed / ((buffs&debuffs)*(haste rating/10000)). With full raid buffs and a 2h weapon this ends up being 3.6/((1.155)*(1+haste rating/10000)). If you’re wondering why haste is on the bottom, remember we’re looking at the interval between hits, which should go down as haste goes up.
To put this into context, with 1000 haste fully raid buffed you would melee once every 3.6/((1.155)*(1+1000/10000)) = 2.8335 seconds. Assuming full uptime on the boss this would result in about 60/2.8335 = 21.175 auto attacks per minute (aa/min).
Now that know how to find the aa/min, we can find out in terms of aa/min and multistrike rating.
If we have x hits per minute, and a y% chance at a z valued proc per hit, our total value per minute is going to be x*(y/100)*z. For example if you roll 2 dice a minute and every time you roll a 1 you get $5, on average you would get 2*(16.6667/100)*5 = $1.67 per minute. I show you this now so you know whats going on when we combine all our stuff so far into a fairly messy bit of algebra. Since we can proc once or twice, we need to split the math up accordingly.
(aa/min * (% chance for 1 proc)/100 * 15 RP) + (aa/min * (% chance for 2 procs)/100 * 15 RP) should give us our total RP/minute from multistrike. We could write this all out as one big function of haste and multistrike, but it’s messy and for the most part useless without context. What we have here is enough to find what we want given a certain haste and multistrike. Let’s find out the amount of RP/min given by 1000 haste and 1000 multistrike.
aa/min becomes 60/(3.6/((1.155)*(1+1000/10000))) = 21.175
chance for 1 proc from ms becomes 2*(1-((1000/66+15)/100))*(1000/66+15)/100 = 0.4212, or 42.12%
chance for 2 procs from ms becomes ((1000/66+15)/100)² = 0.0909, or 9.09%
put it all together and you get:
21.175*.4212*15+21.175*.0909*30= 191.53 total RP per minute from ms auto attack procs with 1000 haste and 1000 multistrike! huzzah! well hold on, because 88.141 RP/min of that comes from the base 15% of multistrike we have with 0 ms rating and 1000 haste, so the 1000 multistrike rating actually only gets us 103.39 runic power for the whole minute. Once you factor in the rp/rune cycle from t60, This turns into 4.08 Death Coils, for a total of 81.6 Blood Charges per minute. PER MINUTE. That means it takes nearly a full 1.23 minutes to get a full Death Strike.
In comparison, that same amount of mastery gives us an extra 18.182% Blood Shield, AND an extra 9.091% AP, which means a larger initial Death Strike heal as well. There is simply no comparison from a mitigation point of view.
Shadow of Death buff
Ok but what about the Shadow of Death buff?
Surely 103 RP per minute will add up to some hp! Well each Death Coil adds 3% hp for 30 seconds, so 3.45 DC/min turns out to be roughly 3.45*1.5 = 5.175% it’s a 6.11% hp gain per minute. Remember that you’re constantly losing this buff while you gain it, so that’s not a stacking hp per minute. In other words, it’s a very minor HP increase for a very large amount of stats.
EDIT: forgot to include t60 talents for the HP calculation. It’s actually 6.11% hp gain, not 5.175%.
For raw survival, we need an incredible amount more haste to make multistrike meaningful for mitigation, and the hp buff we get is miniscule. There are ways they could make Multistrike more valueble to us from a survival point of view, however. Simply adding some mitigation on proc other than (even in place of) the RP would be a fantastic start. Maybe a shield that you get every auto attack proc or something. ANYTHING but RP. As long as multistrike stays in its current form, it’s simply not going to be fixed with numbers.
The frustrating thing is we DO want multistrike, but only as a way to boost damage. It’s very similar to running crit in MoP, in that it was great for damage but terrible for survival.
TL;DR, multistrike (for survival) is poo poo.
But Reniat, how do I know how much multistrike I should have?
YOU DIDN’T HELP AT ALL!
Unfortunately there is no “you should have 1.5 times more mastery than haste”. It’s simply a matter of finding the sweet spot for you as a balance of damage and survival. Feel squishy and in need of more mitigation? You should drop ms where you can and go for mastery. Do you feel you want to do more damage and are willing to take a survival hit? Consider adding multistrike. There is no “right” amount, and the ratio you pick is 100% subjective. The only “wrong” amount of multistrike is if you CAN get rid of more but choose not to, while you are dying to not enough mitigation