The Death Knight is a fantastic DPS class. With three specs to DPS (yes three) there are so many different options as to how to hurt your enemies. As a general outline, Blood provides hard hitting 2h abilities with self healing included. Frost is either 2h or dual wield Haste hits with lots of AoE and CC. And Unholy relies on hard hitting diseases and the Ghoul pet to plague your enemies even after your death. A Death Knight DPS is specced purely to their preference.
DPS-ing at a glance
So when the Death Knight starts, you have an ability of each type and Death Coil, with your racial. Not a very big mix or abilities but it gets the job done in Acherus. A good rotation is to apply your diseases and then hit with any moves that scale with the number of diseases applied. Plague Strike, Icy Touch, then Blood Strike is a really good one to start, burning your excess Runic Power with Death Coil. Once you get access to Blood Boil, Pestilence, Death Strike, and Obliterate, things get much more interesting.
Moving on, in Blood, you'll want to be in either Blood Presence or Unholy Presence. If you see your health in the low a lot, Blood Presence will heal you for 2% of all damage done (increased by Improved Blood Presence). Unholy Presence is for those who have really mastered the rotations of Blood and are ready for a decrease in wait times for GCD and runes. Also, with the Improved Blood Presence talent mentioned above, Unholy Presence is the choice for you because you will gain the healing effect here as well. Moving on to the rotation. The rotation criteria for Blood is very simple. Get in your diseases, then Death Strike to burn the extra runes and get some Death Runes to fuel your constant Heart Strikes. Death Runes are gained by Death Rune Mastery in the lower Blood tree. My typical rotation is below: Plague Strike: To apply Blood Plague. 10 Runic. Icy Touch: To apply Frost Fever. 10 Runic. Death Strike: To burn extra Unholy and Frost runes, change them to death runes, and heal for a decent amount. 15 Runic. Heart Strike: Most powerful move, affected by diseases. 10 Runic. Extra Blood Rune: Depending on the situation, I like to leave a Blood Rune open sometimes to maximize survivability or damage output. A well placed Pestilence can net you much more DPS (in a multi target situation) then a Heart Strike. But generally, this is burned on Heart Strikes. Runic Power: Burned on Death Coil or Rune Strike if the tank is generating enough threat and if you have 3/3 Subversion talents. Rune Strike is more DPS, but is somewhat conditional. More Notes: Your diseases should last much longer than this rotation, so only use Plague Strike/Icy Touch as openers or if your diseases run out with more than 20% health.
In Frost, things are fast and furious. Each Presence serves its own purpose. Also, for the sake of time saving, 2 things. I am not re-linking all of the abilities and things you can find above. And, I will be abbreviating Runic Power RP. So first thing's first. Presence selection is a variable of DPSing in Frost. If you want to self-heal because you see your health going down a lot, use your Blood Presence. Another way to take care of this is get high-armor items and use Frost Presence to increase mitigation through armor and stamina. As another option (and again, as sort of a "Master" Presence) use Unholy Presence. The speed increase will be amazing with all of the Haste you will have in Frost. *Personal Experience* I have frost DPS'd H HoR with a Tyrannical Beheader (Scourgelord Tyrannus, Heroic mode Pit of Saron) and hit with a 1.50 second speed. I topped a t10 arcane mage by 10% DPS against Falric.*Exit Memory Lane* So back to the Haste bonuses, you will hit really fast and really hard with a 2h, but the choice is yours: 2h or Dual Wield. The Rotation for Frost revolves around AoE and CC-ing your enemies, as well as being faster and more resilient then them. This has nothing to do with Resilience unless you are PvPing. So here is the rotation:
Plague Strike: Apply Blood Plague. 10 RP. Icy Touch: Apply Frost Fever. 10 RP. Obliterate: High Damage low cost burst. Better if it doesn't consume diseases. 10 RP untalented. 15 talented. Blood Boil: AoE burst. Blood Boil: Aoe Burst. RP burn: Frost Strike is the only rational choice for a high damage strike. Notes: If you Glyph it, Howling Blast is shifted with Icy Touch to AoE spread Frost Fever. Hungering Cold can spread it too. But generally, Hungering is only used in intense situations with many mobs. A great time to pop Hungering is, if you want the title, hatch all the Rookery Whelps and pop it once they aggro on to you for an easy kill, especially if combined with Howling, Blood Boil, and possibly Death and Decay.
To be added...