Once upon a time, in a patch not long ago, Unholy DK’s did quite well for themselves as far as DPS.  Well fingers crossed, these changes will help keep that streak alive.  But be warned – the Death Knight you once knew has been changed.  So keep your head out of your butt and your mind on the business at hand (a.k.a. Killing Stuff), and one day soon you’ll be putting the HOLY back in Unholy.

Y’know, like “Holy Crap you’re doing alot of damage!”

It was clever, I know.  Shut up.

Talents

A 5/0/31 talent tree seems to be the most popular one out there, and even the spec at Elistist Jerks isn’t much different.  There are changes that can be made to the glyphs, using Glyph of Death and Decay & Glyph of Icy Touch for AOE fights.

Rotations

As far as rotations go, here’s what the pros are saying:

Single Target

Say good bye to the rigid, fixed rotations of the past, and hello to the priority-based playstyle of Cataclysm:

Diseases > Dark Transformation > SSif both Unholy and/or all Death runes are up > FeS if both pairs of Blood and Frost runes are up >
DCif SD, 100 RP, will overcap RP with anything else or if RC isn’t up > SS > FeS > DC > HoW.That likely looks much more intimidating and, in general, complicated than it actually is:

Keeping up diseases is, as it’s (almost) always been, the most important thing, partially for their own potent damage, but primarily because they boost everything else we do. While diseases may only last 33 seconds and Outbreak has an unreducable 60 second cooldown, Festering Strike will bridge the gap, making it so you never have to resort to IT or PS in regular play on a single target.

Then comes Dark Transformation, whose uptime needs to be maximized for optimal dps. DT boosts your Ghoul’s damage by a truckload – a straight up 100% buff overall, plus a 20% Claw specific boost, on top of Claw then cleaving. The second you can DT, you do – no exceptions unless, of course, your ghoul is unable to attack the boss at the time.

You never want to waste runes, which is why SS and FeS when both of their respective rune costs are up comes next.

Just as you don’t want to waste runes, you don’t want to waste potential Sudden Doom procs (by having it just override a yet-to-be-used current one), runic power, or potential Runic Corruption (by having back-to-back procs), which is why you prioritize DC here.

After all of the above is factored away you simply SS, FeS, and DC. The order doesn’t actually particularly matter unless the mob’s death is imminent – in which case you go in that order. If you can, you want to try and avoid back-to-back Death Coils, due to the aforementioned potential loss of RC uptime.

It’s worth noting that on a fight where a npc is constantly healing itself and you can count on the full absorb to be consumed (and the prevented healing would have meant that much more damage needing to be dealt), Necrotic Strike does replace Scourge Strike in your rotation.

A reminder: all of this is done in Unholy Presence.

Multiple Targets
The AoE rotation isn’t terribly different from the single target one:

Diseases > Dark Transformation > Death and Decay > SSif both Unholy and/or all Death runes are up > BB + IT if both pairs of Blood and Frost runes are up >
DCif SD, 100 RP, will overcap RP with anything else or if RC isn’t up > SS > BB + IT > DC > HoW.Whenever you apply diseases, you also want to then spread them with Pestilence. As long as there’s at least one mob up who will survive for their full duration (or, of course, more mobs who may live for less), Pestilence is worth it.

Death and Decay is an AoE juggernaut as much as ever (although, yes, Dark Transformation is still more important due to the cleave). As long as there are three mobs who will be in the effect for at least 8 ticks (or two mobs who will be in it for all 12 ticks, if you have it glyphed), DnD is worth using.

Blood Boil use, for Unholy, always results in a leftover Frost rune which one has no choice but to use for Icy Touch. The two, in combination, replace Festering Strike in your rotation. As long as there are three or more mobs present, BB + IT is worth using in place of FeS.

When AoEing, you should always switch to Frost Presence.

Everything else remains relatively unchanged.

More info over HERE.