Festering Strike is a weird but welcome addition to the unholy rotation. The unexpected use of both frost and blood runes is jarring at first, but makes a weird sort of sense once you've had a chance to think on it more. It takes care of the problem of all those GCDs spent on an extra frost move by simply removing Blood Strike from the equation, and the physical damage and unique rune cost means that it's probably not useful enough for frost or blood to take and mess up their own rotations or power balances. Of course, what it actually does for the unholy tree and the unholy rotation is a bit more complicated, so it's worth discussing.
Festering Strike's extra disease duration is a unique and fun mechanic that, since it seems to have no internal cooldown, actually allows our diseases to extend beyond 1 minute in duration, allowing for the use of Outbreak as our main disease application process and makes our opening rotation (Outbreak > Scourge Strike > Scourge Strike > Festering Strike > Festering Strike) very elegant, then adds extra flexibility to the rest of the battle, as Festering Strike turns the runes into death runes via Reaping. The downside to this is when we kill the mob so fast that Outbreak isn't yet up when it's time to switch targets. This leads to our being forced to use the much less elegant, traditional Plague Strike and Icy Touch. The opening salvo for this (Plague Strike > Icy Touch > Scourge Strike > Festering Strike > Blood Strike) leaves us with that extra Blood Strike hanging out there, which makes the whole thing feel a bit more complicated than it should be.
One way to fix this would be to add something to the unholy talent tree (possibly to Corrupting Strikes in place of the Plague Strike damage buff) that would allow Festering Strike to either refresh diseases spread by Pestilence to full power (instead of the 50% they're currently at) or reduce the cooldown of Outbreak by up to X seconds per application of Festering Strike. This would allow us to keep a consistent, elegant, fun rotation that would transfer easily from mob to mob and that would be markedly different from frost or blood.
If the use of Outbreak isn't meant to be the main disease application ability of unholy, then I'd go back to that hanging blood rune. The fact that Festering Strike doesn't completely remove Blood Strike from our rotation could lead to confusion and annoyance further down the road, since it leaves us with yet another button to push. It's going to take a bit of getting used to, between that and figuring out how to use runes that are refreshed with Runic Empowerment, but it's a bit hard to test how frantic such a rotation really feels, as the rune UI and rune refresh rates are a bit buggy on the beta servers.
Overall, Festering Strike can be quantified as a success, depending on how development of it goes forward and how that Outbreak issue above is resolved. The biggest question gripping the beta death knight community right now seems to be what to name it. The most obvious option, FS, is already taken by Frost Strike. Some people are putting forth FeS as an option, which makes some sense and rolls off the tongue well enough. Others are suggesting that Festering Strike officially take over the FS label, with Frost Strike becoming FrS. Finally a small but vocal contingent want to call Festering Strike FFS. This is certain to be a gripping issue that will rock the death knight community for months to come. We'll keep you updated, I'm sure.
Rune UIs, early trees and other persistent beta issues
While Festering Strike is looking good, there's still some issues with death knight trees and mechanics that feel like they need a little or a lot of polish. While some of them were somewhat shined up in the latest build, some problems still remain. It's worth discussing what could really use a fix in the next big build.
First of all, the default rune UI needs extensive work. It's bugged something fierce, so that often times, runes that are displayed as ready aren't ready, and it often doesn't properly refresh runes refreshed by Runic Empowerment. In addition, with the new rune system, the basic six-rune system doesn't really work that well to show exactly what's going on with your runes. I'd like to see a new display set up something like three separate energy bars, such as in this mockup created by beta poster Eflow. Of course, it may be possible (I'm not an addon creator, so I can't say for sure) that someone could create an addon that does this, but it seems like the rune system has changed enough that Blizzard should be doing this by default. Really, I'd like Blizzard to get this sorted out just so it's easier (or possible) to accurately test rotations and DPS and threat levels.
Another issue remains with the lower trees. The frost tree, especially, is still looking like a pretty horrible secondary tree for PvE DPS or tanking. With the incredibly long length of Frost Fever, most DPSers are not going to have an Icy Touch that is cast often enough to make Improved Icy Touch worth it. Icy Reach is strictly superfluous, since in PvE it is relatively easy to close distance and start DPSing or tanking. Nerves of Cold Steel, while perhaps nicely placed for those who want to try dual-wield tanking despite the lack of threat, is completely useless for two-handed-weapon-wielding DPSers, which means even two-handed-weapon-wielding frost death knights will find themselves taking filler in the first tier. In other words, frost's first tier needs work. Improved Icy Touch feels like it needs to be completely reworked to provide an effect that'd be more useful for a death knight from another tree. The second tier now has On A Pale Horse, but otherwise, all second-tier options remain strictly either for PvP or for frost PvE DPS only.
Unholy's first tier is slightly better than frost in that Virulence and Epidemic provide bonuses that have a more tangible (if still arguably somewhat marginal for blood and frost) benefit, but the second tier is somewhat underwhelming. Frost uses Frost Strike for its runic power dump and therefore will be missing half the benefit from Morbidity. Unholy Command is strictly a leveling and PvP talent and Resilient Infection primarily a PvP talent. I'd generally suggest removing Unholy Command and putting something a bit more enticing in its place, giving frost and blood knights a decent reason to off-spec into unholy besides the fact that frost's first-tier talents are largely useless. As it is, at the moment, I imagine smart frost DPSers will just make blood their secondary for Blood-Caked Blade and Bladed Armor.
And while we're at it, I'm going to harp at it again: Improved Blood Presence needs more goodies for blood tanks. Forcing blood tanks to take two late talent points just to be able to tank competitively is pretty boring and annoying. I actually can't help but think the perfect use for Improved Blood Presence would be to allow it to "steal" some of Frost Presence's runic power generation. Blood right now is seeing an inordinate amount of dead space in which all runes are on cooldown and runic power is low, and more runic power would at least allow one to throw out a Rune Strike or Death Coil in hopes of triggering Runic Empowerment.
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