Regarding specing for desecration for LK: id imagine it would depend on your raid comp to a large extent. Id initially specd it to help out, but our fury warr started getting pissed when she couldnt apply hamstring. Then between a mutilate rogue, paladin tank w imp hoj, resto sham w frost shock in addition to hamstring we found desecration was actually detrimental given the mobs can fly out of it given a poorly placed defile. We also basically disallowed pet stuns, as our rog was seeing 1ish second 5 point ks, after the initial hoj by our paladin tank.

Again, will depend on your composition, but specing for desecration may not be in your best interest, especially if it overwrites other snares that can't be walked out of.

Just a couple of things that Id like to clarify for people.

In my opinion, its better for the raid, and obviously our dps, to have a warrior just spec into piercing howl. Our raid also typically has 3-5 paladins and 2-4 rogues so stunning the adds is not an issue. The sooner you can use your stuns the more you can get some incidental aoe damage on all 3 of them. Assuming you execute properly in stacking up.

Also, if you cast pesti while LK is casting his Vile Spirits cast, you can get some aoe damage up on them. Id link our WoL but we dont have them up yet from our LK kill. Also, using chains on the spirits as they come down is very helpful for the raid if you see one chasing someone / a group at ranged. Kind of kills dps tho :/

As mentioned as well, you can taunt the spirits, so if you have ams/ibf and you can grip tuant/grip one to soak some damage its well worth it. Just be careful not to die. Best to just have the raid spread out in this phase.

I think my point was missed. Obviously, everything in under some circumstances has a potential use (referring to glyph swapping). The purpose for these forums should be maximizing efficiency-yes, you can find some gain for GOD/GODD in other phases, but WILL result in 1) enhancing your aoe numbers in P1; and 2) reducing your single target numbers in P2/3. I would even go so far as dispute the efficiency gain in P1, if you're taking longer to push LK into P2. I don't think this is even debatable, and I am sure that I'm not inventing an issue out of an inability to efficiently pestilence the valkyr.

Despite the DMB timers, the Valkyr always swoops in right before the defile is cast. This means that it's probably a useful opportunity to stun, then back out as a defile is incoming. If it's on you, or you have to run around the puddle for other reasons, there is no reason not to COI on the move. Even if it isn't, the movement reduction from desecration is vastly inferior to COI: While you may sacrifice personal dps on the valkyr, you give everyone else in the raid more time to kill it. With that said, I fail to see the logic in sacrificing talent points to pursue a less effective raid strategy.

I was unaware that DND hits the ghosts, thanks for that clarification. Adding to P3 mechanics, you can also pestilence/BB your diseases to/upon them.

Chains is a GCD. Unless you blow your death runes you're only getting 2 chains out at 2 GCDs and zero damage. Desecration applies a snare to the whole area without sacrificing any damage. Also useful for Heroic, and I suppose normal, Saurfang/Valithria. It's a shame that the Unholy tree is so ridiculously bloated (I'm looking at you Desolation) that you need to drop dps points to get it, but honestly the sacrifice of roughly 1 maybe 2% of personal DPS for the utility is pretty minor.

EDIT: Also I wanted to reiterate the point that wasting pages upon pages of GoD vs. GoDD discussion has been proven time and time again to be futile. It always comes down to a roughly 1-2% difference in overall DPS and a playstyle change (in terms of single target DPS). There has never been data one way or another to definitively say that GoD is or isn't a huge difference. Everybody should really just let this one rest.

Chains of ice (tooltip): "Shackles the target with frozen chains, reducing their movement by 95%. The target regains 10% of their movement each second for 10 sec."

I take your point that it is possible for COI to work differently in a boss encounter-in fact I agree that it pertains to this fight. I can, however, tell you with certainty that COI slows the valkyr MUCH more than 50%-probably the full 95%. Despite the original speed reduction, however, the valkyr definitely regained movement speed much faster than indicated by the tooltip. So we can consider two scenarios: One where you are applying full DPS to the valkyr but it's only slowed 50%; and another where you're just spamming COI and working in PS and DC when the rune is on CD. Unholy is not a bursty spec, and compared to a ret paladin, hunter, and arcane mage(referring to my raid comp), our damage is almost inconsequential.

On the point about the defile always coming AFTER the valkyr, let me first stipulate that I'm talking exclusively about the 10m version, and only in situations when they are both going to occur within a small window of time (approx 3-4 sec). This was a very helpful insight for us, since the timers coincided about 2/3 of the time: We would group up when the timers ticked to about 3sec., wait for valkyr to pop, and then stun/run out for the defile so that it's not dropped in the middle, then chains spam while weaving in DCs and PSs. It is also useful to have your AMS up for this: Whenever the defile was on me, I would keep going straight, pop unholy pres. and circle around-sometimes ranging me from the healers if there was another puddle in the way. The AMS can preemptively absolve the infest, should it be cast while I was on the move.

I'd like to see some more feedback on this mechanic, because it nearly trivialized the second phase for us and I'd like to see some others benefit from it as well.

Yes, because chains of ice only lasts so long and you'll eventually be on rune cooldown unable to continiously cast it on the mobs, not to mention you wouldn't be dpsing very well at that point either really just casting chains which again, detracts from your overall dps. The mobs are slowed to a max of 50 so having a cons. down is a lot more forgiving for dpsing/moving/getting out of the defile if its called.

Also, pop ams when the ghosts are coming down (not sure if it was suggested or not) as you can soak all the exploding damage from them.

Chains definitely does not work as advertised for the Valkyrs, pretty sure it doesn't slow initially beyond 50%. Why they decided to not allow COI to work yet they're stunnable is beyond me.

I'm sure that's the design philosophy, but it's sort of a cop-out reasoning when the Valks are generally dead by the time you run out of stuns. Sure it would trivialize it in 10man, but in 25 you're not ever going to have enough runes to perma-snare 3 Valks, and certainly not while doing some sort of DPS.

Long story short - due to COI having a stealth nerf on it for that encounter, Desecration is neato to have there if you're willing to drop 1% personal DPS into it. In terms of general raid benefit, that's a pretty small sacrifice.

Sure, one DK in your 25 man wouldn't be able to keep 3 Valks locked down but what about the guilds that raid with 2-3? That's also not taking into account the DK stacking guilds would inevitably do for that fight, if perma-snaring Valkyr's was possible. Handling the Valks correctly is arguably the hardest part of the encounter, and there is no way around the fact that full effect CoI would be overpowered there.

Edit: No, Frost ist not the best sub-spec.

CoI will never outdamage IT.