Death Knight Class Guide

Runes and Runic Power
Mana, energy, or rage may have been what your WOW Gold eyes paid very close attention when you were first leveling up. You needed to carefully watch how much mana you used or else you'd be out and either being chomped on by nasty monsters, watch how much energy you had before you used an ability or else you'd be cutting yourself short on your next ability, or monitor your rage and make sure you were getting enough to use your abilities. Runes and Runic Power work differently than either of these three.
As a Death Knight you'll have six rune shown below your health bar. You will have two Blood, Frost, and Unholy runes. Abilities will use a set number of runes that when used will make that number of runes go inactive for 10 seconds until they're recharged. So let's say you're giving a Murloc quite a bit of a thrashing and you use an ability which costs one Blood and one Frost rune. For ten seconds one of the two Blood and Frost runes will be unable to be used. So if you had an ability that used two Blood runes then you'd be out of luck.
Now, if you played a Warrior on your way to fifty five then you're in luck. Runic Power works a lot like Rage. You gain runic power every time you use a rune. Some abilities work off of Runic Power meaning that you'd be able to unleash them after you've used enough abilities that were powered by runes. Runic Power depletes over time like Rage, so be sure you use it up when it's available!
Certain abilities can affect the recharge on runes or even convert them into Death runes which will work for any of the three rune types. Mixing these abilities into combat can really help you finish off enemies faster and show Murlocs an extra good trashing.
You can find a more in-depth look at Runes and Runic Power in our sub-guide here: Runes and Runic Power.
Presences
Death Knights have access to personal aura like abilities called Presences. They provide powerful buffs to you that help you to fulfil your various roles. The presences are continuous effects, and will last until you change them. You can only have one active presence at a time. The benefit provided depends on the presence, but they can provide extra damage, extra health, extra threat, and more.
If you are doing damage in PvE then you will mainly be using Blood presence or potentially Unholy. If you are tanking, then you will be using Frost presence for extra health and threat. If you are fighting in PvP combat then you will be using Unholy for faster attacks or potentially Blood, depending on your build and the situation.
Character Stats
Being a hybrid class capable of melee DPS or Tanking, Death Knights rely on many statistics. The primary stats depend on what role you are attempting to fulfil in your group. If you are tanking then you are looking for Stamina, Defence, and Avoidance. If you are DPSing then you need to focus on Strength, Hit, and Crit.
Strength - Increases your Attack Power thereby increasing your damage.
Stamina - Increases your health points. This is critical for tanking since you will take a beating.
1 Stamina = 10 Health points
Agility - Agility increases the following: attack power with ranged weapons, armor, critical hit chance and your chance to dodge attacks. The ranged weapon bonus is meaningless to Death Knights since you can not use ranged weapons. The armor bonus is also relatively small since we can use plate armor. The main reason to boost agility is for the critical hit % and dodge %.
Defence - Defence is a key stat for Tanking Death Knights. The more you have the less chance an enemy will be able to critically hit you. At level 80 you need 540 defence to be able to tank without suffering critical hits.
Hit - Hit is critical for Death Knights but essential for DPS Death Knights. At level 80 you need 295 Hit rating to ensure that you do not miss with melee attacks. This number drops to 263 if you are a Draenei or have one in your party.
Expertise - This stat is another critical one for DPS Death Knights and important for Tanks as well. You need 123 expertise at level 80 as Blood or 172 as Frost or Unholy to reach the soft expertise cap. There is a hard expertise cap but it is significantly higher and not completely necessary. The soft cap prevents your attacks from being dodged, while the hard cap prevents them from being parried as well. DPS only needs to aim for the soft cap since they should be attacking enemies from behind, where they can not be dodged anyway. Tanks can aim to reach the hard cap since they will be attacking from the front but need to ensure they are not sacrificing too many other stats.