3. TANK STATS
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The following are tank stats:
effective health (armor | stamina | mastery)
avoidance (dodge | parry)
threat (expertise | melee hit | strength)
3.1 EXPERTISE
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Expertise decreases the chance that your melee abilities are dodged or parried by the boss.
Your melee abilities are those based on weapon damage: Blood Strike, Hearth Strike, Plague Strike, Death Strike, and auto attack.
At level 85, a level 88 raid boss has a 6.5% chance to Dodge attacks from all directions, and a 16% chance to Parry attacks from a 180?? arc to his front. Expertise decreases the chance of a boss dodging or parrying your hits in 0.25 per point. This means you would need 26 to avoid dodges, and 56 to avoid parries.
To reach 26 expertise you only need 32.79 *20 = 655 expertise rating because we get 6 expertise from "Veteran of the third war". From 80 to 85, the expertise needed to prevent dodge is 23 and not 26.
3.2 HIT
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A Death Knight has both melee and caster abilities:Spell abilities: those not directly related to weapon damage, that is: Icy Touch, Howling Blast, Death Coil, and Pestilence.Melee abilities are those based on weapon damage: Blood Strike, Hearth Strike, Plague Strike, and auto attack.
Death Knight spell abilities are not affected at all by spell damage.
Hit is the source for two different stats: Melee hit: you get 1% melee hit per 120.109 melee hit rating.Spell hit: you get 1% spell hit per 102.446 spell hit rating.
To avoid failing your hits against a boss you need:17% spell hit (1741 rating) for spell abilities (only 6% in heroics). 8% melee hit (960 rating) for melee abilities.
3.3 PLAYING WITHOUT HIT OR EXPERTISE
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What happens with 0 expertise?
The boss will dodge and parry 6.5% and 14% of your attacks.
What happens with 0 hit?
You will miss 8% of your melee attacks, and 17% of your spell attacks.
What happens when you fail an attack?
If an ability is fueled by runes, the runes are not used, and you lose the 1.5 seconds of global cooldown that it takes to repeat the ability.
If an ability is fueled by Runic Power, the Runic Power is lost. Note that Rune Strike can't be dodged or parried by anyone.
What is the chance of failing DS?
In blood spec and 0 hit/expertise from gear you have 8% miss + 5% dodge + 12.5% parry = 25.5% chance to fail against level 88. That is 0.255*0.255 = 0.065 (6.25%) chance of failing 2 DS in a row, and 0.255^3 = 0.016 (1.6%) chance of failing 3 DS in a row.
9% avoidance (or 9 mastery) is a HUGE protection and offsets by far the risk of being 1 DS away from death and failing that DS. This would only change if in some heroic mode you are guaranteed to go down to 10% hp or so (I don't have any experience in heroic modes).
How about interrupts?
The logic behind playing without hit and expertise is that the benefit of getting survival stats outweigh the risk of failing an interrupt.
If you are in a normal 5man or raid, you should survive. If you are on a heroic 5man or raid, there are spells that will kill you depending on your gear. On such cases, maybe, you'll want to invest on the Virulence talent or increase your hit in some way.
How about tank DPS?
Only important enough if you are running against a timer enrage. And even then, think twice how important that is against your survival.
3.4 THREAT
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It's a non issue in raids thanks to Vengeance. Vengeance provides 5% of damage taken in attack power up to 10% of our hp. When we start a fight we should receive Tricks of the Trade or Missdirection to increase our threat, and later we stack enough Vengeance to keep our threat very high.
If you don't get have enough threat, there are several explanations: Your playstyle. Your gear. Too many target changes. Mobs apart from each other so you can't cleave with Heart Strike. Everyone burning their cooldowns at the start, and rogues/hunters not boosting your threat.
3.5 ARMOR
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Armor mitigates all damage except bleed (a kind of physical damage) and spells.
Effective Health is how much your health would be if you had no damage reduction or avoidance but could still take the same amount of hits. You can increase effective health getting armor and stamina gems.
As armor goes up, it takes more armor to get each extra percentage point of damage reduction, but that's countered by the fact that each additional point of damage reduction is more valuable than the last to increase your time to live. So in terms of absolute time to live, armor is not subjected to diminishing returns.
On a purely physical fight 11.7 armor equals 1 stamina in terms of effective health. eg: the Glyph of Indomitability trinket has 1792 armor, which equals 153 stamina. On Sindragosa the damage is 60% magic, 40% melee so it would be worth 153 * 0.6 = 91 stam.
If an item has the armor in green in its tooltip, it means that it has more armor than other gear of the same level.
See the following for related math:
http://www.wowwiki.com/Armor http://maintankadin.failsafedesign.c...rb_v=viewtopic http://www.tankspot.com/showthread.p...569#post230569
Base armor of a Death Knight is increased to 51.6% thanks to 30% Blood Presence, 10% Toughness, 4% Stoneskin Gargoyle, 2% Austere Shadowspirit Diamond.
Damage reduction from armor for levels 81 and above is:
DR% = Armor / (Armor + 2167.5 * attackerLevel - 158167.5). AttackerLevel would be 88 for a boss. The number you see in the armory is calculated for an attacker with the same level as the player.
Total damage reduction is calculated multiplying damage reduction effects:
% DR = DR from armor * 0.08 Improved Blood Presence * 0.06 Blade Barrier.
You should be able to keep Blade Barrier active most of the time (you have to keep your blood runes in cooldown for this).
3.6 RACIALS
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Racials reward you with mobility, threat, and survival. These are the best imo: Alliance: Night elf for +2% miss or dwarf for 10% less damageHorde: Goblin for +1% passive attack speed and other cool stuff. Like rocket boots (very useful in pve too) that work as blink, a banker NPC, and ranged damage for PVP. See the full list here:
http://www.wowwiki.com/Racials
OR choose whatever you love the most. You will be looking at your character for a long time. Some thoughts to help you decide: Expertise bonus = bad, you get the caps from gear anyway, and reforging 3 expertise to stamina is still bad. Spell resistance = bad. Most of the damage is physical. Tauren 5% base hp and Draenei heal are straight bad, they don't scale.
Disclaimer: This is not my own guide and do not take credit for it. You can find the original work here.