With that in mind, I went with a 3/31/7 spec.
It's important to note that my aim is to be able to do two things well with this spec. The first, I'd like to be able to DPS in a PvE environment competitively. The second, I'd like to feel useful in PvP Battlegrounds. Thus, some points are chosen for that sort of utility, even though I know it makes my spec not "the best" raiding spec or "the best" PvP spec. It's a hybrid spec. For instance, my PvP needs are what entice me to spec into Chillblains and use the Glyph of Hungering Cold. You may want to go another route if you're wanting a pure raiding spec.
In the Frost tree, I laid off Icy Reach, Chill of the Grave, and Endless Winter. I may swap the points I spend in Butchery for CotG just to see which generates more RP. I'm happy with Butchery right now though and don't feel RP starved. I ignore the 2H Might of the Frozen Wastes since I'm DW, and also put a point in On a Pale Horse. It's nice to be just a bit faster in BGs.
In the Unholy tree, I extend my disease length and put two points in Unholy Command (mostly in order to get to T2 but it doesn't hurt for PvP). In the second tier I pick up Desecration. My playstyle in PvP revolves around controlling and slowing the opposing players. With the combination of Desecration and Chillblains (Plus Hungering Cold and Chains of Ice thrown in), I've found it pretty effective. Especially when protecting siege vehicles and such.
In the Blood tree I just take Butchery and put my last point in Bladed Armor. I may eventually take points away from Desecration and fill up Bladed Armor (maybe even just one point) if I feel that I'm overdoing the "slowing" approach. For now, though, I like it.
- Major Glyphs - Pillar of Frost, Chains of Ice, Hungering Cold- Here's where it gets a bit murky. Hungering Cold for free is good stuff in a BG. It works as both an interrupt and a freeze. I find it incredibly useful. After that, I didn't find myself using Pest as much anymore and went with Pillar of Frost instead for an extra escape. I also didn't find myself needing the extra Strangulate seconds (and wondering how many times I actually procced it since I use Mind Freeze as my interrupt), so I went with Icy Chains, which I use all the time. I contemplated Dark Succor for the healing, but, again, I just don't find myself using it enough. Your mileage may vary.
Intro: Howling Blast > Plague Strike > Necrotic Strike > Blood Strike > Obliterate > Frost StrikeAdded NS into my "setup" phase. Also added a bit about DS:
You also get Dark Simulacrum, which is a very neat spell to use, especially in PvP. Basically it lets you steal any spell that uses mana and then use it. Cool stuff and the possibilities are endless. Have fun with it and throw it in when you can. I like to steal heals in PvP and heal myself. One little bug I've noticed is that DS doesn't really work inside of a macro. I had to have it on it's own key to get the second spell to work, or it'll just tell me that "I haven't learned that spell." It'll do the original cast of DS well enough, just not the "borrowed" cast. I don't know what it is about being in a macro that messes this up, so I've just put it on it's own key straight from the spellbook.
I've been having a blast with this chica in BG's. Having leveled this later as an alt, I find myself a bit behind the gearing curve of the general PvP public, but I can still hold my own. With the changes in 4.0.6 we retain our ability to eat mages for lunch, and also gained some added protection against stuns (and rogues). Good stuff.