Death Knights

Specs:

If you are looking to be a dps death knight then i'd probably say that unholy is the best spec to have. Not just because its the spec i am, but it has great talents for improving dps. Some people will probably shout "but blood is great! it heals you!" which is why i think blood is best left to the pvp'ers.
If your looking to be a tanking dk theres quite a few different specs you can try. A lot of dk's like frost spec for tanking because it has the talents to increase armor and melee haste, but there are many successful dk's who use unholy or blood spec combinations.
There have also been some debates as to whether using a 2H weapon or dual wielding is better for a tank. My personnal experience was that a 2H is much better as you can make and hold aggro much better than when dual wielding, because a lot of dk'd attacks are based on weapon damage.

Its probably best to just try out a couple of different talent trees to find what works best for you.

Glyphs:

As an unholy dk probably my favourite glyph is:

- glyph of scourge strike: 25% chance of causing blood plague and frost fever. this may seem like an odd glyph, but it means that you dont have to use your runes to reapply diseases, and so can use the runes for more damaging attacks, and therefore you do more dps

This is probably the most essential glyph, but for the other 2 glyph slots, again its probably what you find most useful.

Written by Emy, relocated by Summonus

Is this at lvl 80 for raiding content or for levelling up, because I suggest that for solo levelling that Blood would be the best. This is just what I have found when I have been levelling up to 80 (And still am), as it allows you to fight Elites on your own and mostly come out on top. This is because of the great self healing of the Blood Death Knight, in fact the other day I soloed a mob with 100K health! Anyway, that's what I find the best way to level, I will probably go Unholy as Emy has suggested once I get to 80.

Mort

Yeah, what i was talking about in my 1st post is for lvl 80 raiding and i completely agree that for lvling blood spec can be really good

I thought that I'd just post a bit about levelling as a Blood DK, don't worry I'm not going to go into all sorts of technical talents mumbojumbo; I just want to explain about some of their skills and a good rotation I have found.

Ok so basically a Blood Levelling DK is all about survivability, because this is great for soloing elite mobs and pvping. So other than having a lot of self-healing a Blood DK is a bit like an Arms warrior.

Blood only skills:

Rune Tap: This is an excellent Blood spec skill that you should invest points in, it isn't far down the tree either, so if you want to multispec you can easily get this. It converts one blood rune into 10% of your health and just below it in the tree is Improved rune tap, if you invest 3 points in this it will increase Rune Tap to 20% - couple this with Vampiric Blood (explained later) and you get a whopping 30% HP restored. Not bad eh?

Mark of Blood: This again costs just one blood rune. Mark of Blood is a curse/debuff you put on your enemy that means that when that mob deals damage to it's target, the target regains 4% of their maximum health, it lasts for 20 seconds.

Hysteria: This ability can be used on the DK or a friendly target. Hysteria lasts for 30 seconds and increases the damage of the person who has the buff on them by 20% but they lose 1% of their health every second. I personally find this rubish as it just loses you health when soloing, I think it would be better to use it when in groups as the healer can compensate for the loss of health.

Vampiric Blood: Basically it costs one Blood rune and increases the health generated by spells and effects by 50%, useful for soloing if you want to beef up Rune Tap and good in groups because the healer won't need to use as much mana on you.

Heart Strike: This is a basic melee attack, it costs one Blood rune. Heart Strike does 60% weapon damage + 220 extra as well as 110 per disease on the target; additionally it prevents the target from using haste effects for 10 seconds.

Dancing Rune Weapon: This ability basically makes a clone of your weapon (That floats in mid air, cool or what?) for 10 seconds, it costs 50 runic power but the time limit increases by 1 second per 5 additional runic power. The weapon will do the exact same attack moves as you; this means you can apply 4 diseases onto your target! which should beef up your Heart Strike even more!

Okay so thats the Blood abilities explained, now I'll explain what rotation I use. I generally use Unholy Aura when soloing but for harder fights I use Blood Aura and when it's even harder I use Frost Aura; it really just depends on what you really need most. The rotation I use goes something like this:

Icy touch - Plague Strike - Blood Strike - Heart Strike - Obliterate - Death Coilx2 - Rune Strike (if it is possible to use it). By now you should have finished off any normal mob, but if it is a harder one like and elite I then follow up with: Icy Touch - Plague Strike - Blood Strike - Heart Strike - Death Strike (this should provide a bit of healing to top you up) - Death Coilx2 - Rune Strike. Now if they still aren't dead rinse and repeat, if you need extra healing miss out Blood and Heart Strike and replace with Rune tap and Vampiric Blood!

Well thats it! My smallish guide on how to play a Blood Levelling DK!

Mort

im lvling my dk as unholy with a few points in blood (manly for 20 RP each kill) and finding it so easy any mobs that look a bit harder than norm and i say one thing ' get him pet' and things like bone shiled and the gargoly make it even easyer and faster and if i ever do die im right back killinging it as a undead lol andwho dont like courps explotion

Deathknights are the next best thing to a Paladin in my view, i have chosen Unholy talent tree from lvl 55-80 and i must say the amount of aoe i produce is insane. Being unholy has alot of advantages, first off on a pale horse increases your mount speed just like a paladin with crusader aura, secondly you can have a undead ghoul as a pet for life which in some cases can save your ass, i have found a glyph that does not cost any corpse dust so your pet is free to summon from now on instead of 45s per raise. At lvl 80 you get a spell called Army of Dead, which is a 30 min CD that summons 8-10 ghouls to fight for you up to 1 min they have 4.5k hp and taunt and attack everything, yet another great thing about unholy tree is at the cost of 50 runic power you can summon a gargoyle too. Eat your heart out hunters lol. Who doesnt want to a be Warlock/Pala in Plate