Overview

Death Knights received comparatively few new talents compared to other classes. This was partially due to the huge amount of talents that were shifted around between the trees. At various stages in Wrath of the Lich King each Death Knight tree has been viable for tanking, that's going away. Blood has been designated as the new tanking tree for Cataclysm, and has been given nearly all of the tanking abilities from the other trees. Staple abilities like Bone Armor from Unholy and armor increases from Frost have been moved to the Blood tree, and frost will now be a dedicated DPS tree.

New 4.0.1 Talents

Unholy:

Runic Corruption - Reduces the cost of your Death Coil by 3 per talent point, and causes your Runic Empowerment ability to no longer refresh a depleted rune, but instead to increase your rune regeneration rate by 50% per talent point for 3 sec. (2 points)

Shadow Infusion - When you cast Death Coil, you have a 33% chance per point to empower your active Ghoul, increasing its damage dealt by 10% for 30 sec. Stacks up to 5 times. (3 points)

Dark Transformation (Active!) - Consume 5 charges of Shadow Infusion on your Ghoul to transform it into a powerful undead monstrosity for 30 sec. The Ghoul's abilities are empowered and take on new functions while the transformation is active. (1 Unholy Rune)(1 point)

New Active Talents

Blood:

Bone Shield - Okay, so this isn't new. It's a pretty big change for Blood though! Surrounds the Death Knight with 3 Whirling bones, each bone absorbs 20% damage from any source and the DK deals 2% more damage with all abilities while Bone shield is active. Lasts 5 mins. 1 min cooldown.

Frost:

Pillar of Frost - Calls upon the power of Frost to increase the Death Knight's strength by 20%. Icy crystals hang heavy upon the Death Knight's body, providing immunity against external movement such as knockbacks. Lasts 20 sec. 1 min cooldown.

Unholy:

Unholy Frenzy - Induces a friendly unit into a killing frenzy for 30 sec. That target is Enraged, which increases their melee and ranged haste by 20%, but causes them to lose health equal to 3% of their maximum health every 2 sec. 3 min cooldown.

New Passive Talents

Blood:

Scarlet Fever- Gives your Blood Boil a 50% chance per talent point to afflict enemies with Scarlet Fever, reducing their physical damage dealt by 10% for 30 sec. (2 points)

Hand of Doom - Reduces the cooldown of your Strangulate ability by 30 sec per point. (2 points)

Sanguine Fortitude - While active, your Icebound Fortitude reduces damage taken by an additional 15%/30% and costs 50%/0% runic power to activate. (2 points)

Crimson Scourge - Increases the damage dealt by your Blood Boil by 20% per point, and when you Plague Strike a target that is already infected with Blood Plague, there is a 50% chance per point that your next Blood Boil will consume no runes. (2 points)

Frost:

Brittle Bones - Your Strength is increased by 2% per point and your Frost Fever chills the bones of its victims, increasing their physical damage taken by 2% per point. (2 points)

Might of the Frozen Wastes - When wielding a two-handed weapon, your autoattacks have a 15% chance per point to generate 10 Runic Power. (3 points)

Unholy:

Resilient Infection - When your Blood Plague or Frost Fever is dispelled, you have a 50% chance per point to have the rune cost refunded. Does not apply to diseases spread via Pestilence. (2 points)

Sudden Doom - Your autoattacks have a 5% chance per point to make your next Death Coil cost no Runic Power. (3 points)

Analysis

Death Knights in Wrath of the Lich King were an extremely versatile class capable of filling many roles. An unfortunate side effect of that versatility was that they lacked a clearly defined role in many situations with each tree being a muddle of defensive, offensive, and utility abilities.

Cataclysm talent trees are significantly less muddled. Most of the passive defenses have been removed from Frost and Unholy and given to Blood. Each of these trees were compensated for the loss of an active ability by receiving a powerful active damage dealing cooldown.

One of the most notable changes is the removal of some of the area of effect abilities. Wandering Plague, which is arguably the most powerful passive AoE in the game, is gone. Talents that passively increased diseases like Crypt Fever have also disappeared. This is not surprising, however, given the systematic nerfing and removal of AoE abilities that has been going on in the Cataclysm Beta.

Frost underwent some massive changes for the better. The tree was streamlined incredibly, condensing the long and expensive talent chain to get Improved Icy Talons to just 1 talent point down from 9. With the removal of tanking talents and addition of another strong raid buff in the form of Brittle Bones and a very powerful damage cooldown - Pillar of Frost - the Frost tree is looking very appealing.

Blood is the true enigma of the three trees. It has been completely redesigned and stacked with great tanking talents. With the obscene amount of cooldowns that Blood Death Knights will have (Antimagic Shield, Bone Armor, Icebound Fortitude, Rune Tap, Vampiric Blood, Dancing Rune Weapon, not to mention Will of the Necropolis), they will be absolute beasts for tanking assuming that their armor and evasion is brought in line with the other tanking classes. On paper, for now, they look amazing and this could revitalize DK tanking which has been effectively dead since patch 3.2.

4.0.1 Change Analysis

Unholy has been the go-to spec since the Death Knight class came out and has in many ways come to define the class, particularly with the use of the permanent ghoul pet. Thus, it came as no surprise that when Unholy was underperforming in the Beta they gave it some pretty massive buffs, and those buffs primarily revolve around the Ghoul pet.

There's no better way to put it than that the newly buffed DK Ghoul is absolutely insane. Using the new Shadow Infusion talent you can quickly get to 5 stacks of the buff (totalling 50% additional Ghoul damage) and then put your pet straight into its Dark Transformation mode. Here's a quick list of the fun stuff that you get with Dark Transformation:

Cleaving auto-attack

4-5k DPS on its own

100% increased damage during Dark Transformation

The pet is now a huge source of Unholy's damage, and in addition it now scales with the Death Knight's haste and critical strike (though the critical strike portion is currently bugged and not working). The pet is an absolute killing machine, and it's very easy to put it into Dark Tranformation mode. This mode can be maintained for the majority of the time you're actively engaged in combat. All you need to do is dump 5 Death Coils into your target, activate Dark Tranformation and you're off to the races. The buff lasts 30 seconds, and if you're careful watching your timers you can have a full bar of Runic Power waiting when the tranformation ends which you can use to cast more Death Coils and begin the process anew. Runic Corruption, the last of the new talents added feeds into this playstyle by reducing the cost of Death Coil.

Here's a quick video of the new abilities Shadow Infusion and Dark Transformation: