I know DP isn't exactly the best talent choice in that tier, but I've just been trying it out and wondered if anyone else came to the same conclusion about it.
In general, its accepted that its usually best to cast inquisition with 3 holy power for, meaning you only have to cast cast it (roughly) every 30 seconds. But DP has a 25% chance to proc off of ANY ability that uses holy power (regardless of the number of hp it uses).
So my thinking is this - wouldn't it be most efficient, while using Divine Purpose, to only cast 1 hp inquisitions? It triples how often you have to cast it, but that means you have triple the chance of having DP proc from it. And you effectively get 3 free holy power for the price of 1, rather than for the price of 3.
The rotation gets a little more complicated, but I'm just wondering if any people who use Divine Purpose play this way - as I couldn't find much information on it.
As you know with MoP comming live they changed DP chance proc chance back in Beta. So if you cast Inq on 1 hp you have less chance getting proc from DP then doing that on 3hp. I remember back in beta I think it was holy when picked up DP got like crazy amount of procs when using WoG on 1 holy power. So now if you use at one holy power chance to get proc is 8%, with 2 holy power 16% and with three ofc 25%. ( or something in that order)
Refreshing Inq every 8 sec is dps loos. Cause every 30 sec you'll be down for 2 GCD. True we sometimes have couple empty GCD but in this case you'll prob remove them at cost of not squeezing 2 extra attc in every 30 sec, which may be lets sax Exo (missing out 2p T15 debuff) or CS (even if it's rng you may miss couple extra holy TV's).
The 25% proc chance is only for casting an ability with 3 holy power. The proc chance is proportional to the number of holy power used in the spell. 1 HP = 8.3% chance. 2 HP doubles the proc chance to 16.7% and 3 HP triples to give you a 25% chance to proc.
Even without that math, casting inquisition with 1 HP is always a dps loss, barring cases where you get many DP procs in a chain. If you assume that you have 25% DP proc chance regardless of your HP used (which is not true anyway), you're going to get 1 DP proc roughly every 4 inquisition casts. In that time, you waste 2 gcds because Inquisition only lasts 10 seconds instead of 30. Additionally, those 2 gcds that could have done damage would also have generated holy power. Since you could presumably have generated 2 more holy power with those gcds anyway, you're net result is 1 extra holy power in exchange for the loss of 2 gcds and some damage.
Basically, barring extremely good luck, it's not good to cast inquisition with only 1 HP. The only exceptions to this are when you are unable to hit the boss (maybe during a transition or movement phase) and only if your holy power is going to deplete unused if you don't cast inquisition.
That definitely makes sense - I've always thought it would make sense for the proc chance to be greater the more HP you have, and it sounds like that is the case.
But if it were true - I think with some tweaking it could have been beneficial. You aren't always losing a GCD to cast it inquisition with 1 hp, partly because we don't always have an ability to use for every GCD, and partly because there's a way to generally thread in a 1 hp inquisition immediately your rotation. If you open with an ability, cast inquisition, you can still have a rotation where you actually don't lose many GCD's (thanks to our new 5 hp cap).
But I guess that's all irrelevant because of the reduced DP proc chance. Thanks for the help