UNHOLY DK PVE

BY THE WAY, I THINK FROST DPS IS MUCH BETTER THEN THIS SPEC
YOU SHOULD CHECK OUT THAT WRITEUP

This is a 2H spec
I. Here is a link to my spec

II. Glyphs:

            A. Raise Dead

            B. Scourge Strike

            C. Death Coil

            D. Pestilence

            E. Anti-magic shell

            F. Blood Boil

            G. Horn of Winter

            H. Blood Tap

            I. Resilient Grip

III. STATS:

Hit to cap > Strength > Haste > Crit > Mastery > Expertise to cap > Agility
IV. ROTATION:

Single Target
Diseases > Dark Transformation > SS if both Unholy and/or all Death runes are up > FeS if both pairs of Blood and Frost runes are up >
DC if SD, 100 RP, will overcap RP with anything else or if RC isn’t up > SS > FeS > DC > HoW.

Keep up diseases
Dark Transformation (uptime needs to be maximized for optimal dps)
You never want to waste runes, which is why SS and FeS when both of their respective rune costs are up comes next.
DC
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 potential loss of RC uptime.

Multiple Target

Diseases > Dark Transformation > Death and Decay > SS if both Unholy and/or all Death runes are up > BB + IT if both pairs of Blood and Frost runes are up >
DC if 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.

V. FLASKS, FOOD, CHANTS, and PRESENCE:
            Flask of Endless Rage
            Strength Food or Fish Feast

            Weapon Enchants – Rune of the Fallen Crusader
            ALWAYS STAY IN UNHOLY PRESENCE

VI. REFORGING
Follow this thought process when reforging as an Unholy DK:
Are you hit capped?

If yes, then reforge any excess hit into haste, if it’s not already on the piece as well, and to crit if haste is.

If no, then reforge any expertise, mastery, and then crit – in that order – into hit until you reach the hit cap.

Does the piece already have haste?

If yes, then go to the next question.

If no, then reforge any excess hit, expertise, mastery, and then crit – in that order – into as much haste as possible.

Does the piece already have crit?

If yes, and it also has haste/hit (as it should following the previous two questions, then there’s no need to touch it.

If no, and it already has haste/hit (as it should following the previous two questions) and another stat, then reforge the extra stat into crit.

*Secondary stats mean ratings (and Spirit, not that we care about that).