The Death Knight is the newest addition to World of Warcraft, and has since undergone many changes. Initially, the ideal Death Knight Leveling Build was the Blood Tree, while Frost Death Knights were tanks. Now, however, Blood is the tanking tree, while Frost and Unholy are the DPS specs. However, if you are looking at a Death Knight Leveling Build, I would strongly suggest the Unholy tree, for a number of reasons.
Speed – Even before you get Unholy Presence, you can spec into Improved Unholy Presence to receive the constant 15% movement speed increase. Since the majority of time questing is actually travel, you will definitely benefit from this over any of the other specs. Frost’s talent, “On a Pale Horse” is a great talent for movement speed as well, but only affects mounted movement speed, while Unholy Presence buffs movement speed at all time.
DPS – OK, both Frost and Unholy specs have great high end DPS. However, with an Unholy Death Knight Leveling Build, you have more consistent DPS. Frost Death Knights rely on procs and burst damage, while Unholy is consistently powerful. A Frost DK can easily down a mob in 3-4 seconds or even less. However, without procs like Killing Machine or Rime, it’s more like 6-7 seconds. With an Unholy build, you’re right in the middle at 4-5 seconds. Over the course of 5-10 kills, Unholy pulls out ahead with more consistent damage. In fact, when chain pulling Unholy becomes more effective because you can activate Dark Transformation and then your Ghoul really starts kicking out the damage.
Survivability – Frost has some very limited survivability mechanics. Hungering Cold and Lichborne are essentially your only options for escape or self healing as a Frost Death Knight. However, with an Unholy Death Knight Leveling Build, you can still spec into Lichborne, you have your ghoul to eat up some of the damage for you, a lower cooldown on summoning your ghoul if you need to use death pact, and the combination of a movement speed bonus, as well as a speed debuff to your targets with Desecration is more than enough to avoid incoming damage or escape to safety.
Mass Killing – Here is where the Unholy Death Knight Leveling Build really pulls ahead of Frost. As Unholy, you get a powerful boost to your diseases through talents like Epidemic, Contagion, Ebon Plaguebringer, and your mastery, Dreadblade. This boost to your diseases allows you to pick up multiple mobs, and burn them down while kiting them through your desecrated ground, and letting your ghoul finish them off.
When you combine these factors, you have a powerhouse in your Unholy Death Knight Leveling Build. As a second spec, you can always choose Frost, though I would recommend you pick up Blood. With Blood you can pull larger groups or meaner elites and still walk away.
However, the proper talent spec isn’t going to do the job if you don’t know where you’re going. You need to follow an optimized path in order to really get the maximum experience per hour. In order to get to level 85 in the shortest time possible, you need to follow an optimized questing route in order to compliment your Death Knight Leveling Build.