Originally Posted by
Brusalk
I'll try and explain what they're saying Vampiroth.
Devouring Plague should only be cast while we have 3 orbs. As a result, after getting 3 orbs we have at 8 seconds before we can get an orb again, at which point we want to have cast DP already so we don't potentially waste either MB casts/fight or orb generation.
Now, spells like Halo which have a GCD are limited in the max number of times they can be cast per fight based off of how close you actually are to casting them on GCD. What they're saying is that if you hold off on casting DP for a DoT refresh, or casting a CD spell like halo or mind-bender, you're not losing any potential damage from Devouring Plague but you are gaining potential damage from being able to cast a CD spell more in a fight or having higher dot uptime. I actually agree with them that because of the orb generation DP+3 shouldn't be highest on priority, and instead CD spells or other dots should be higher. However, that only holds for the first 6 seconds(4 gcds) after getting 3 orbs.
Now, where it gets a bit complicated is that if you have divine insight, rather than it being a set "DP+3 is lower on priority than x" for 4 gcds after getting 3 orbs, you have to be concerned with getting 2 DI procs in those 6 seconds. As haste increases it gets more and more likely that we will get a proc in those 8 seconds from a SWP tick.
Probability of getting a proc off of one tick: 15%
Worst case we have 3 ticks of SWP in those 6 seconds. (first just after the MB cast that gets us 3 orbs)
Probability of getting getting 1 or fewer procs in three ticks: 93.9%
Probability of getting 2 or 3 procs in 3 ticks: 6.1%
As you can see, the probability of getting 2 or 3 procs in those 6 seconds is quite low. (The thinking here is that if you get a DI proc you have until you get a second one to use it up, otherwise you lose the first one. Also, I'm guessing that the number of times you'll get a DI proc mostly negates the effect of the case where you don't get a DI proc before the CD on MB comes up from the first proc'd cast)
As a result, it's most likely still a DPS increase to cast a dot refresh or a cd spell before DP until you get a DI proc, at which point you should cast DP and then MB to reduce the chance of munching the first DI proc with the second.