People don't understand tanking ...

While it's nice to have 'Borgthor is main tank' exclaimed in all caps with a redundancy of exclamation points, there is a serious trend in over simplifying what makes a good tank.

In this case, we were getting ready to take on some Horde home city bosses in a 40 man raid. There was already a guy informing people he was main tanking the bosses, when the raid leader asked us to pst our HP. 28k, and a confirmation that it was unbuffed (of course) was all it took to provoke the raid warning.

Now I looked at the other guy (a pally), and as far as I could see he was similarly geared, sensibly chanted and gemmed. There was also another prot warrior, waiting quietly at Chillwind Camp, who was WAY better geared than both of us.

So to quickly dispell the myth... having the most HP does not make you the best tank. Here's my quick guide about the total package that is the tank...

Firstly, I'm going to assume that for anything remotely dangerous (where you might die) a tank will be uncrittable.

Effective Health

Effective Health is a measure of how much raw damage it takes to kill a tank, assuming the tank does not avoid damage (dodge / parry / miss) or block. For magic, damage is mitigated (reduced) by resistance. For melee, damage is mitigated by armor. Most discussions ignore magic damage, but it's important to know that total HP (and resistance gear) is king for coping spell damage, particularly since magic attacks cannot be dodged, parried or blocked. For most fights however, it makes more sense to concentrate on reducing the incoming melee damage...

Armor reduces the damage taken from melee attacks, and the best way I've seen it's importance described is from the tankspot article on effective health theory, "Even though this may sound obvious, it needs to be repeated that every increase in Armor gives linear and potent scaling to the effectiveness of Stamina. Every increase in Armor is a direct increase in the effectiveness of Stamina; every increase in Stamina is a direct increase in the value of Armor."

If two tanks have HP (and attributes below) in the same ball park, the one with the most Armor will be able to take the biggest beating.

Avoidance

A tank's avoidance is the measure of how often they are able to avoid melee damage attacks altogether. A tank (but not all tanks, see below) can avoid attacks by being missed, dodging or parrying. Many statistics contribute to increasing avoidance:
- Chance to be missed is increased with defense rating
- Dodge is increased by agililty, defense rating and dodge rating
- Parry is increased by defense rating, parry rating and strength (DK only)

The more avoidance a tank has, the more often melee attacks will inflict no damage, the less healing that has to be done. However, while armor guarantees melee damage reduction, avoidance is based on probablities. If a tank has 50% avoidance, there will be times when a mob will hit (or miss) many times in a row, which is why tanks concentrate on getting their effective health to the minimum level required by content before concerning themselves too much with avoidance (which is heavily itemised on most tanking gear anyway).

If HP and Armor are in the same ball park, the tank with the higher avoidance will be able to take the bigger beating.

Comparing Different Classes

Not all tanks are created equal, and Warriors, Paladins, Druids and Death Knights have their own strengths an weaknesses. In italics above, there's lots of in the same ball park. While Blizzard have worked hard to make sure all tanks can tank most things, there major differences between the tanking classes that can make them hard to compare. For example:

Warriors and Paladins can use a shield and can block. So we get another source of damage mitigation based on block percentage and block value.

Druids can't parry, are automatically uncrittable with talents and usually have high dodge, armor and HP. A similarly geared druid and warrior tank will have different levels of HP, armor and avoidance in order to survive the same battle.

Death Knights can dual wield, or use two handed weapons to tank. They gain avoidance through strength (an important threat stat) and have a high armor modifier when tanking.

Add to this the different skills available to the different tanking classes, and it's not as simple as comparing total HP to decide who is best for the challenge. As a raid leader and guild master I have been learning more about the other tanking classes in order to best utilise them while raiding - I may write something on that in the future.

Threat and DPS

There is more to tanking than not dieing! While in WotLK the threat game has largely declined (so far), it has been replaced with tanks being able to dish much higher DPS. A tank that can make a significant contribution to party/raid DPS will help get those bosses down.

For a warrior, important threat stats are expertise, hit, strength/attack power/block value. Particularly expertise and hit are important for early on in a fight where if you get dodged, parried or miss a couple of times, an eager DPSer (or healer even) could end up on the pointy end of a sharp stick.

If all else is equal, take the Tank that can push out the most DPS.

Tanking Skill

Gear is important to a tank! Developing a well rounded meat shield that can take a beating, and have enough avoidance to avoid gobbling up all the healers mana and push out some credible damage takes a lot of work. However, all the gear in the world won't make up for a player that doesn't know their toon.

Tanks have an enormous array of offensive and defensive abilities to reduce incoming damage and bring the pain! A smart healer won't blame themselves for losing a warrior tank that doesn't know how to use shield bash or spell reflect to reduce avoid spell damage. Smart DPSers know the difference between playing with a tank that can weave all those new AOE tanking abilities into a pleasant AOE fest through and instance. One day, the healer may even thank you for understanding how to weave your AOE stun, mob attack speed / attack power reduction and defensive abilities together for when those pesky DPS have all but forgotten that sometimes, single target DPS is still useful.

Take the time to appreciate your tank. Don't just reduce them to a number. If they can talk about their experience and gear intelligently and are geared enough to have a go at the content, give them a go! They may just be a friend you haven't met yet.