Now, assuming you like to tank, you should also be comfortable with the tools for the job. The four tanking classes each tank in a different way. If you don't like the way your tanking class tanks, you're probably not going to perform as well as you could otherwise. I don't like the current implementation of druid tanking, and I'm fairly certain I became a better tank when I switched to my DK for tanking instead.
I won't say anything about effective health, and very little about mitigation and avoidance. This post is not aimed towards the all-high elitists who will switch tanking class if the other has 5% more effective health or whatever. Besides, I lack the time to invest into the theorycrafting necessary for that kind of analysis, and the experience to be able to talk from an empirical point of view.
Resource managementI assume you have a basic understanding of the resource systems available in WoW. But, veeery quickly; DKs have a dual-resource system of runes and runic power. Most abilities cost one or more runes. Each rune expended will refresh itself after 10 sec, sometimes less. All rune attacks generate runic power. Some abilities cost runic power to activate.
Because of the nature of the runes and runic power, DKs have the exact same resources available to them no matter what kind of content they're tanking.
Paladins use mana as their resource. No tanking gear has intellect on it, so a paladin only has the base mana pool of their class, modified by Arcane Intellect, Mark of the Wild and Blessing of Kings, depending on the raid setup. They burn through mana rather quicly, and have a three major ways to regain it. First, they regain mana constantly with Divine Plea, which with talents have a constant uptime as long as you're fighting. It is affected by int buffs. Second, they regain mana when they block, dodge or parry an attack, as long as they've buffed themselves with Blessing of Sanctuary. Since it also grants -3% damage taken, it's a very bad idea not to buff yourself with it when tanking. Third, they regain mana by being healed.
The mana gained from Divine Plea is near constant, no matter what content you're facing. It's only affected by buffs, so usually a bit higher in raids than in 5-mans because the chances that there's a mage, druid, and several paladins increase the more people there are. The mana gained from Blessing of Sanctuary is much higher when tanking multiple mobs than a single mob. It is about the same when facing a single raid boss and a single 5-man boss. The mana gained from being healed depend on how much healing you need, so it is much higher in raids than it is in 5-mans.
Druids (and warriors) have a rage system which generates rage on hitting and being hit, and depend on how much damage they take. Thus, they generate a lot more rage in raids than in 5-mans.
It seems to me that Paladins are balanced around having infinite amount of mana available, and druids and warriors are balanced around having infinite amount of rage available, when it comes to raids. Unfortunately, it means that sometimes the three tank classes will go around mana/rage-starved in 5-mans, especially if they're overgearing the content. Less problem now than what it was, but it's not unheard of of paladin tanks to take off some of their armor when tanking 5-mans, to regain enough mana to get the job done. Ever seen a pants-less paladin? Not to be confused with a pantsy paladin.
Resources vs cooldownsThe nature of the rune system means DKs can't spam the same attack times and again. They will (in most cases) run out of at least one type of rune after 2 consequensive attacks. That means that their rotation is primarily limited by the resources, namely the runes, and almost no attack used in their rotation has a cooldown. There is one notable exception: Death and Decay has a cooldown. It's rather annoying, too, in my opinion, because the minimum cooldown of 15 sec talented doesn't fit with the 10 sec rune cooldown, meaning you have to hold back some runes if you want to cast it on every cooldown. A "simple" fix would be to use it every 20 sec instead of every 15 sec, but sometimes (like Halls of Reflection) you need it RIGHT NOW.
On the other hand, both a rage and a mana system allows a character to hit the same attack several times in a row. In fact, were it not for cooldowns, most tanks would be spamming the highest-threat ability all the time. Imagine a tank spamming Thunderclap or a paladin spamming Hammer of the Righteous against AoE packs. To avoid that, all of a paladin's attacks have a cooldown attached to it. As far as I've understood, the ability is put on cooldown even if the attacks fails to connect. In most cases, a paladin tank just have to worry about managing these cooldowns with a proper rotation, and can safely ignore the mana issue. However, tanking low-level stuff and content you overgear tends to make you bang your head into the keyboard for lack of mana all the time.
Druids (and warriors) have a similar design, however, both have a "basic attack" they can spam to no end (Sunder Armor / Lacerate). All other attacks have cooldowns. To avoid tanks spamming their basic attack all the time, all other attacks available to these tanks generate higher threat, and should be prioritized.
RotationPaladins, with their cooldown-based tanking system, have a true rotation, dubbed 96969. It comes from the fact that if you use the abilities in the wrong order, you end up having no abilities not on cooldown somtimes, while at other times several abilities refresh from cooldown at the same time. To avoid that, you alternate between six-second cooldown moves (Hammer of the Righteous and Shield of the Righteous) and nine-second cooldown moves (Holy Shield, Consecration and Judgement). There are no real nine-second cooldown abilities, all the mentioned have 8 sec (talented) CDs. However, if you alternate these with the six-cooldown moves, you generate max threat, and they sort of "work" like they were on a 9-second cooldown each.
The rotation is so strict that you could create a macro for it. However, any tank worth his or her salt should do it manually, because the various attacks have different priority depending on the situation. For example: Hammer of the Rigtheous hits several targets, and should be earlier in the rotation than Shield of the Righteous against multiple enemies. However, against a single enemy, SotR outthreats HotR. And so on.
Druids can also have a true rotation, at least on single target fights. Highest priority is... Feral Faerie fire, ironically enough. At least last time I checked, it provided the most threat, and for the cheapest price... for free. But most use Mangle, which activates some idols and applies the debuff. All free global cooldowns should be filled with Lacerate.
If you don't put talents into Mangle, the rotation is simple; Faerie fire, Mangle, Lacerate, Lacerate. If you put talents into Mangle, there is no longer a rotation, but a priority queue: Mangle on every cooldown, Faerie fire if it's up, otherwise Lacerate. Reason: If you give priority to Faerie Fire then Mangle, both will come off cooldown the same moment, so you don't get any benefit from talenting Mangle at all. Macro Maul to activate on all the mentioned attacks.
On AoE fights, you just hit Swipe every global cooldown. If you have a single mob you need to keep sticking to you, mix in a Faerie Fire, Mangle, or both, betwen the Swipes. That makes them different from paladins: They need to choose either to generate max single target threat or some AoE threat. Paladins just use the same rotation regardless of whatever is hitting you, with the possible exception of adding Holy Wrath against multiple undead or demon mobs.
A DK doesn't have a true rotation. "True" as in you know what button you're going to hit every global cooldown. They have more of a priority system. Knowing what to hit every GCD is a matter of knowing how your abilities interact with each other, assessing the current situation, and knowning what resources you have available... in effect, which runes are off cooldown. I'm not planning to write a "DK tanking 101" now, if you want more details, have a look at Gravity's excellent site pwnwear.com.
The short version is that you have a priority like this:
- Keep diseses up on all mobs.
- Spend your runs whenever they come off cooldown to generate as much threat as possible, on the targets you want threat on. That's a bit messily written, easier with an example. Let's say a blood rune comes off cooldown. Do I want to spend it immediately on single-target threat (Blood or Heart Strike, depending on spec), AoE threat (Blood Boil), wait for a frost and unholy rune to throw down a lot of AoE threat (Death and Decay), or refresh diseases on all off-targets to avoid them falling off (Pestilence)?
- If all runes are on cooldown, spend Runic Power, but only if I have enough to spare that I won't be starved when I need Runic Strikes.
Runic strike deserves a special note. It is not an instant attack, but an "on-next-melee-hit" ability, like Maul and Heroic Strike. It's usually macroed to every single attack, for ease of convenience. I think it was designed to let DK tanks put their spare runic power to good use, rather than just let their runic power be capped at 100% all the time. Unlike dps, a DK tank's rotation must be adjusted to whether they hit or not. Many aren't hit capped, and even if they are, bosses parry, dodge and block a lot of attacks from the front. Since rune attacks have higher priority (since they do more damage) than runic power attacks, DK tanks don't usually have any GCDs to spare to use runic power attacks at all. Anyway, no matter what the original design was, Runic Strike is vital to generate max threat, and should be used as often as possible.
When I explain it like this, DK tanking sounds really hard. It is certianly harder than druid tanking, but then again, bear tanking rotation is so easy it's trivial (flame me a comment if you disagree). Any addon that shows the status for each rune will make the job a lot easier. I can't say if it's harder than the paladin rotation or not. For the moment, I've got far too much training in DK tanking and far too little in paladin tanking. I find DK tanking to be really "logical". At least after it was cleaned up, each DK ability has it's spesific use, and it's woven really well together. Compare that to paladin, which is much more "brute-force"; No abilities depend on each other to do increase threat, like most of a DKs abilities depend on having the diseases on a target. You just hit the attacks in the order of whoever generates the most threat, with the notable exception that Holy Shield has highest priority because it also adds in mitigating incoming damage.
Keep it up, buddyAll the tanks have some abilities that must be "kept up" in some way.
A DK needs to keep up diseases on all mobs all tanked mobs all the time. Besides threat, it provides the -20% attack speed debuff that reduces incoming damage. In addition, they need to keep up Blade Barrier all the time, a talent that reduces all incoming damage by 5%. Keeping it up is actually really easy; Just spend runes. The buff is refreshened each time all blood runes (and death runes from the same blood runes) are on cooldown. So if you just attack more or less normally, it will be up almost all the time.
A paladin must first and foremost keep up Holy Shield, to increase both threat generated and mitigation. In addition, they want to keep up Divine Plea as much as possible, since it provides them with mana and -3% damage taken glyphed. It is a bit special; as long as they're hitting something, it's up. It fades if not fighting for 15 seconds, but can be buffed up again immidiately again if it's been at least 1 min since it was last "started". In practice, on boss fights there is very little a paladin can do to prevent it from running out if there's a break in the fight. Finally, to generate max threat and dps, they want to keep up the stack of Vengeance from Seal of Vengeance/Corruption all the time. However, as with Divine Plea, there is very little they can do to prevent it from falling off whenever the boss is not in melee range, such as when it's flying, submerged, the tank needs to run away, etc. They also want to keep up Vindication, but it's virtually impossible not to keep up as long as you're fighting a mob.
A druid must keep up Demoralizing Roar by refreshing it every 30 sec or more often. They also want to keep up Faerie Fire and the Mangle debuff to increase threat and dps for all physical dps in the raid. Both are pretty easy to keep up, as they're a part of the core rotation. Soon, it'll even be even easier since Mangle will last for an entire minute in the next patch. Finally, they want, to a lesser degree, to keep up Lacerate. While it's handy for personal dps, it's not deprimental to threat if they lose it, as the instant portion of Lacerate generates a ton of extra threat, while each tick of Lacreate generates 80% less threat than the damage should imply. Thus, it's sort of "handy to keep up", but not vital.
StickinessIt's of course vital that a tank can keep aggro when he wants to. Short version, if they're doing their job correctly, any tank can hold aggro. If they can't, then they're doing something wrong, or Blizz will most likely buff them very soon. However, there are some notes on differences in how they generate threat.
Mobile threat-generationDruids have no "stationary" way of generating threat. They can move and generate full threat, provided they remain in range of their targets all the time.
DKs have one stationary threat move, Death and Decay. It's a more or less vital part of the initial pull on multiple mobs, but it's not vital after that. As long as they've got diseases ticking on all mobs, they're pretty mobile as well. Most DKs doesn't use Death and Decay after the initial pull, instead spending runes on Blood Boil because they don't have to "save" runes to wait for one rune of each type to be ready.
Paladins have a very stationary threat move, Consecration. In addition to being stationary, it is always cast on the feet of the paladin, as opposed to Death and Decay which can be targetted on the ground anywhere within range. To make matters worse, it has a pitifully low radius. And finally, it's the only way a paladin has to generate guaranteed threat on more than 4 targets. The other three ways of generating AoE threat have limited targets. Hammer of the Rigtheous is limited to the primary target and 2 (or 3, glyphed) more targets, which seems to be picked semi-randomly from the close mobs by the server. Avenger's shield works on the exact same principle. Holy Shield requires a mob to actually hit you when you're blocking, and there's no way to guarantee that a given mob will hit you often enough that it will remain on you. Good thing for them that paladins have so much taunting power. More on that in a moment.
"Your mother!"All the tanks have a single-target taunt on a 8 second cooldown. The paladin version is notable for also generating a fair bit of damage (around 1-2k on a new 80), meaning it's much more likely that the mob will stick to you.
In addition, a druid has Challenging Roar, which taunts all mobs within 10 feet and sticks them to you for 6 seconds, on a 3 min cooldown. Very powerful stuff. 6 seconds is half an eternity in a crisis situation. Warriors have the exact same ability.
Paladins also have another taunt on a 8 sec cooldown, Righteous Defense. Instead of taunting a mob, it taunts up to three mobs targetting the friendly unit you target. Use it with a macro and target=targettarget, and it taunts the selected mob and up to 2 others targetting the same ally. Incredibly handy. On the other hand, since a paladin tank usually isn't hit capped, they often need it to guarantee a tank switch will go smoothly.
Death Knights doesn't have a secondary taunt, but they have a "force enemy to focus on you for 3 sec" with their Death Grip. In a way, the DKs get the short end of the stick here. I haven't felt it was a huge disadvantage when tanking, though. Of course, it's more important when things *not* go smoothly.
Tanking cooldownsTanking cooldowns generally comes in two variants; cooldowns that increase your threat generation and cooldowns that in some way increase your chances of surviving.
Druids have one threat generation cooldown, Berserk. It also doubles as a short fear breaker/immunity on a long cooldown. Mangle looses it cooldown and hits three targets for the duration. Nothing can ever hope to catch you on threat again after you've spammed 10 mangles on a mob.
They have three cooldowns, Barkskin on a 1 min which reduces incoming damage by 20%. Survival Instincts which glyphed increase your max health by a whopping 45%. Cutting-edge bears can hit almost 100k health with his up. Finally, Frenzied Regeneration which converts rage to health. More importantly, glyphed it increase all healing received by 20%.
The druid survival cooldowns feel fairly powerful. They can overlap each other, resulting in a huge survivability increase for a short duration. In particular, I very often combine the latter two while tanking, while I use Barkskin almost every cooldown just to reduce general incoming damage.
Paladins have one threat generation cooldown, namely their pretty wings Avenging Wrath. You might also count Avenging Wrath as a mini-threat cooldown. Their wings increase all damage (and thus threat) by 20%. Besides looking pretty on screenshots (and very unpaladinish, imo) they're really handy for pulling far away on the threatmeters fast.
On the flip side of the coin, paladins have only two real defensive tanking cooldowns unless you spec a bit strangely into the Holy tree. First, they got an active cooldown in Divine Protection. -50% damage taken on a 2 min cooldown. Pretty powerful. HOWEVER, it may not be used within 30 sec of Avenging Wrath, or within 2 min of using Divine Shield or Lay on Hands on yourself. That's kinda annoying. That means you can't freely use Avenging Wrath when you want/need to generate extra threat, you got to know the fight and only throw it if you know you won't be needing Divine Protection for the next 30 seconds. I know that this is because of PVP balance, but I still think it's a bad design.
You can, as earlier mentioned, use Lay on Hands and Divine Shield too, but all three are exclusive with each other because of a 2 min Foreberance debuff. Lay on Hands might be more powerful against weak mobs that doesn't damage you too much, but Divine Protection will almost always trumph it in raids. With the very strange but possible exception that you're low on mana and need Lay on Hands to recover some of your own mana. You can also use Divine Shield, but while it redmoves all incoming damage, it also means that you have an effective threat score of 0 for the duration of it. The only thing that persists through it is "force to attack" abilities. There is one notable way to use it; since it always clears all debuffs without any chance of failure, you can taunt a mob (stick it to you for 3 sec) cast Divine Shield and immidiately cancel the shield (using a macro with /cancelaura). Now you're debuff free, and the mob is still on you. However, you can't use Divine Protection for 2 min. There aren't too many cases where it's worth it.
The other "real" defensive cooldown is the Ardent Defender. It is passive. In addition to reducing all damage taken while at low health, it allows you to survive certain death and recover half your health once every 2 min. It is powerful. It translates to having a health pool at least 1.5 times your size on a 3 min cooldown. However, it's also a last resort thing; You can depend on it, but you (almost) never intentionally use it.
To be fair, they also have some other abilities. Divine Guardian reduces the damage taken by the entire raid by 20% for 6 seconds, but also moves 30% of all the remaining damage to you. It breaks when you're at 20%. The "breaks at 20%" allows it to be used while tanking, whoever it's still risky. While the entire raid may be taking more damage, you may end up taking more. And while you have Ardent Defender to fall back on, it's never a good idea for a tank to intentionally be reduced to 20%.
They can also spend talents to get Aura Mastery or Improved Lay on Hands in Holy. The first can give them a short armor or resistance boost, depending on what aura they're currently using, but it's nothing spectacular. The other will allow them to take -20% physical damage for a period, but causes Forebereance like a normal LoH does, so then you get that and the normal effects of LoH instead of Divine Protection. Finally, they can glyph Hand of Salvation to make themselves take 20% less damage for a short period. That *is* handy, however, you also get the normal effects of salvation, -10% threat. Not so good thing, especially not on threat-sensitive fights like those where two tanks taunt the boss off each other regularly.
I didn't like the set of defensive cooldown a protection paladin has. It feels ... too few. Only one emergency button to hit. While Ardent Defender is really dependable, it's not so overpowering that pallies don't need anything else.
Now, DKs. Cooldowns a-plenty, as mentioned earlier. Quickly going through the list: Icebound Fortitude for some 50%ish damage reduction. A 1-min CD talent depending on what tree said DK is specced into (Unbreakable Armor = more armor, Bone Shield = less damage taken, or Vampiric Blood = health and incoming healing increased). Another talented CD for two of three trees (Anti-Magic Zone or Rune Tap). Raise Dead + Death Pact to instantly heal 40%. Anti-Magic Shell to greatly reduce incoming damage on a 45 sec cooldown, also hindering application of any magic debuff. To a lesser extent Army of the Dead, the act of summoning them grans damage reduction for a short while, usable against spell and unavoidable damage. They can also Death Strike like crazy to heal themselves, often paired with Empower Rune Weapon. ERW can also be used as an offensive cooldown.
The army is a very interesting ability, as it taunts everything BUT raid bosses. It increases your dps, but not your threat. Same with Summon Ghoul.
DKs have a huge toolbox of cooldowns. I love having all the tools available. Not all of them are very handy for raids, but most of them are. My personal all-time high favorite is Anti-Magic Shell, a skill I sorely miss if I'm on any other tank than my DK.
Mitigation and avoidanceA few words on this topic too. Though, a lot will change with Cataclysm.
Paladins block a lot. Usually at least 65% from talents alone. They also parry and dodge some attacks.
Death knights parry a lot. Usually around the same amount they dodge, somewhere around 20% or higher. They can also dodge, but not block.
Druids dodge a lot. Usually more than 40% of the time. They can't parry or block.
Kick, or we wipe!Paladins lack any true spell-interrupt. What is a true spell-interrupt? An ability that's off the global cooldown and that spesifically interrupt spells. They can interrupt with Hammer of Justice or Avenger's Shield, but both are on the global cooldown, making them harder to time properly. As a blood elf, however, I get Arcane Torrent which interrupts off the global cooldown.
Druids have only a ranged interrupt, Feral Charge. Since you spend most of your time in melee range, you have only Bash, a 1-min CD stun to interrupt spells with.
Death Knights have a true interrupt, Mind Freeze, on a 10 sec cooldown. They also have a silence which can be used to interrupt, Strangulate. The latter even has a range. Most handy.
Interrupts are not vital for raids, as you will (almost) always have someone else available who can do the job. However, it is most handy for 5-mans and some raid bosses.
AP debuffFor some reason, Death Knights are the only class without an AP debuffs. Why? Beats me. Vindication and Demoralizing Roar do the trick for paladins and druids.
Poison? Magic? Disease? Mohaha, I'm a pally!Paladins have the special ability to cleanse themselves of a lot of debuffs while tanking. At the cost of some threat. Like interrupts, very handy for 5-mans, less so for raids.
BuffsYou probably know what classes bring which buffs. If you're lazy, Death Knights have the easiest to apply buff, Horn of Winter. Whereas you must be expected to bring reagents and buff people randomly dying as a druid or paladin.
Which buffs are more powerful? I'm not going to say a lot about that. In a raid, you're almost certain to have all the buffs anyway.