A little bit of poking around reminded me of a few fun facts about haste which I’d like to expand on with regards to new NG. First, haste effects are multiplicative. That is, any single source of haste (haste rating, Wrath of Air Totem, Nature’s Grace, etc) is multiplied with current haste level, not added to it. That means the more sources of haste you have, the better all the others become. It also means more haste may increase casting speed faster than we might expect.
More importantly for my talks on NG, though, is that spells have a casting speed lower bound 1 second. Because queueing gets a little odd around the GCD, your latency probably insures that all spells you cast take longer than 1 second even if your haste puts your cast speed there. However, that just alters the lower bound value: the fact that there is a lower bound is what matters.
Obviously, a lower bound to casting time impacts wrath more readily than starfire due to its lower base cast time. Now, in the last post I showed that the number of casts per NG cycle, on average, was independent of haste. That had the further effect of showing that the average haste provided by NG was independent of other sources of haste. However, the cycle duration is dependent on haste. If there is a lower bound on casting speed, that implies there’s a lower bound on cycle durations. That implies that there is a limit on the impact of NG on your DPS, dependent on other sources of haste. In particular, because starfire continues to scale with haste at the point wrath hits the lower bound, then there likely exists some level of haste where starfire scales beyond wrath dps. This is assuming that starfire is not already doing higher DPS than wrath and that wrath doesn’t scale so before hitting the lower bound that starfire can’t catch up to it before it hits the lower bound. These are verifiable, though I won’t do so here. I will, however, take them as given.
This essentially imparts a hard haste cap on wrath v. starfire. Depending on your gear setup, you may be able to exchange haste for other attributes to stay below the hard cap…but deciding if that is the best option will depend on whether wrath scales as well with those stats as starfire does with the haste you give up. Naively the answer will be no, because of the multiplicative effects of haste mentioned earlier. However, that’s also dependent on what point starfire catches wrath beyond the haste cap.
That said, It may prove nigh impossible to avoid haste if you’re doing high end content. Blizzard has liberally sprinkled haste on everything.