Death Knight Tanking: An Early Analysis

I realize that theorycrafting this early in Alpha is largely useless, but that doesn't make it fun!

Death Knights share many similarities with Druid tanks in that they will be unable to use a shield at all; instead they will be mitigating damage entirely through parrying, dodging and massive amounts of armor. As such, the vital stats for DK tanks will be defense rating, parry rating, dodge and armor. It is likely that we will see a lot of gear with mostly defense rating on it, as Blizzard appears to be trying to consolidate gear for all classes, and +defense rating is useful to any tank.

Looking at the currently available gear, DK's will probably be able to attain a base parry of about 20-25%, an overall dodge chance around 30% and a net armor mitigation of about 65-70%. Interestingly enough, with the right talents (discussed below), DK's have the potential to reach the avoidance cap, immunizing them to all but spell damage, which they will be quite capable of coping with (this is, after all, there intended role).

TANKING TALENTS

As advertised, the Frost tree appears to be evolving into the default tanking tree for Death Knights, with supplementary talents mostly in the confined to the Blood tree. The most important talents appear to be:

BLOOD

-Forceful Deflection (5 point): Increases your parry chance by 1/2/3/4/5% as your attack power increases.
It is unclear exactly how this talent will be implemented. Do you get a maximum of 5% parry increase? Do you get 5% additional parry for every X AP? Regardless, increased parry chance is always a good thing and any sensible DK tank will have this talent.

-Spell Deflection (15 point, Requires Forceful Deflection): You have a chance equal to your parry chance of taking 30% less damage from a direct damage spell. 
Any mitigation in spell damage is always welcome, especially considering the Death Knight's intended role as a magic tank. With a parry chance in the 50-60% range from talents, this ability will mitigate about 15% of all incoming spell damage.

-Blade Barrier (20 point): Whenever you have no runes active, your parry chance is increased by 30% for the next 8 seconds.
Another vital talent. As you will be most likely using your runes as soon as they become available in order to maximize your threat, it is safe to assume to you will be runeless at least every 8 seconds, allowing this ability to be constantly active. With this (assuming it works as described), the Death Knight tank will have a constant parry chance of about 55-60%. 

FROST

-Toughness (5 point): Increases your armor value from items by 10%
Self explanatory, more armor is always a good thing. 

-Frozen Rune Weapon (10 point): Imbue your Rune Weapon with Frost. Each hit causes 5.7 – 17.6 (at level 20) additional frost damage, based on the speed of the weapon, and has a chance to cause your target to be vulnerable to frost damage.
The extra frost damage part of this attack isn't too exciting (Windfury will still probably be a better mainhand temp. enchant in terms of damage), but take note of the second part. As Death Knights tanks will be dealing the majority of their damage with frost spells, making the enemy vulnerable to these is a great bonus. More damage = more threat = better tank. This also presents interesting ideas in the 1-hand vs. 2-hand debate, which are discussed later.

-Fridgid Dreadplate (25 point): Enemies who hit you in melee have a 5/10/15% chance to become unsettled, decreasing their attack speed by 50% for the next 3 swings.
Another self-explanatory talent. Slower attacking boss = less damage = happier healers.

-Unbreakable Armor (30 point): Whenever you use a frost rune, you have a 15% chance of increasing your armor by 30% and your parry chance by 30% for 10 sec.
This talents works nicely with Blade Barrier and, assuming you have mostly frost runes (3 or 4), will probably be active for the majority of a fight. If this is the case, most Death Knights will probably see near constant parry chance of around 90%. This seems ridiculously high, and I fully expect Blizzard to tone down the effectiveness of each of these talents in the next alpha patch.

-Frost Strike (40 point): Next Melee; A strong attack that increases melee damage by 200 and causes your attack to deal frost damage. Has a 30% chance to freeze the target.
The Death Knight analog to Heroic Strike. It is unclear whether or not this attack will cause extra threat, but regardless it will be useful to any tank. It's interesting to note that, unlike the other “strikes” a DK has (Plague, Blood, Heart etc.) Frost Strike adds a constant amount of extra damage to the attack, instead of a percentage of weapon damage. 

UNHOLY

-Unholy Command (5 point): Reduces the cooldown of your Death Grip ability by 5/10 seconds and your Blood Boil by 2/4 seconds.
 Faster taunts are always nice, though not necessarily critical for a tank.

-Bone Armory (25 point): The caster is surrounded by 4 whirling bones. Each bone reduces the damage of the next attack against the caster by 40%, but is then consumed. Lasts 5 minutes.
With a cooldown of only 30 sec, this ability would be fantastic if it weren't so deep in the Unholy tree. 


TANKING ABILITIES

-Death and Decay: {Base+AP*0.039} Shadow damage inflicted every 2 sec to all targets in the affected area for 8. Has a chance to cause affected targets to cower in fear. 
Basic AoE tanking ability, with a use similar to Consecration; cast and watch the enemy flock to you. Many people dismiss this ability as it has “fear” in the description, by this effect is thought to simply freeze the enemy in place, similar to the warrior's Intimidating Shout. 

-Anti-Magic Shell: Surrounds the Death Knight in an Anti-Magic Shell, absorbing 75% of the damage dealt by the next harmful spell. Damage absorbed by Anti-Magic Shell energizes the Death Knight with additional runic power. Lasts 5 seconds.
This would have been wonderful to have on the Kael fight in Tempest Keep. Likely there will be bosses with similar mechanics where a Death Knight will be required to use this ability.

-Icy Touch: Deals {Base+$AP*0.2} Frost damage and reduces the target's ranged, melee attack, and casting speed by -15% for 22 seconds.
The effect of this spell will likely be superseded by abilities like Thunderclap and Curse of Tongues, which do that same thing, only better. Regardless, an excellent tanking ability that slows down any damage output of a mob.

-Blood Boil: Causes all disease effects on targets within 30 yards to painfully erupt, consuming the diseases, dealing {Base+$AP*0.1} damage, and forcing the target to attack the Death Knight for 3 sec. 
AoE taunt with a twist that requires the target to be diseased. Hopefully additional DK's in the raid and the new ability that “jumps” diseases from one target to another (I can't remember the name) will aid in the use of Blood Boil.

-Death Grip: Harness the unholy energy that surrounds and binds all matter, drawing the target toward the Death Knight and forcing the enemy to attack the Death Knight for 3 seconds.
Perhaps the most interesting Death Knight ability, taking use of the new knockback mechanics Blizzard is trying to introduce. While it is unclear if the teleport function of this ability will work on bosses, a taunt ability is critical for every tank. 

TWO HANDED WEAPONS VS. DUAL WIELD

It has been carelessly assumed by many that Death Knights are meant to tank with two-hand weapons, taking advantage of parry mechanics to deal damage fast and DPS with a dual wield spec. However, the existing talents suggest exactly the opposite; DK's will tank dual wielding and DPS with big heavy two hand weapons. 

Most of the talents in the Blood tree and most of the Death Knight DPS abilities use some variation of “does X% of weapon and Y effect” indicating a higher damage (two handed) weapon for outputting maximum DPS in a raid setting. 

Conversely, many frost talents seem to be built around the idea that the tanking DK will have two weapons. Nerves of Cold Steel increases your chance to hit with one handed weapons by 1/2/3% and Killing Machine gives your next Icy Touch, Mind Freeze or Howling Blast a 20/40/60/80/100% increased crit chance after a melee critical strike (which there would obviously be more of with two weapons instead of one). Futhermore, depending on how the mechanics of the Frozen Rune Weapon ability work (can you apply it to your offhand only?) a Death Knight tank with 2 weapons would be able to utilize both the Frozen Rune Weapon mechanic and Windfury. 

Finally, with the recent switch of many mainhand weapons to 1-hand, there will be a plethora of 1-hand tanking weapons available. Dual wielding two of these (assuming Blizzard continues to make them 1-hand and not mainhand only) would give the DK tank a huge stat boost over other tanks.