So I took most of the questions I've seen this far, compiled answers from the various points you all brought up in here and over PMs and added a few new Qs and As myself. Please help me proof-read, comment on anything you'd like to see changed/added/removed/moved. Nothing is too minor to report.
I'm fairly sure there are plenty of things that can be added, but it's all too messy in my head right now.
tip: search in this thread (ctrl + f windows, cmd + f osx) with the numbers within brackets next to the questions.
Why is stamina good? 
Why is armor good? 
What is this 'diminishing returns' or DR thing I've heard of? 
Why is parry rating good? 
Why is dodge rating good? 
Why is mastery rating good? 
People say I want different stats or trinkets for different occasions, but how do I know which stats I want? 
What talents for survivability do I want? 
What is this 'unhittability' I've heard about? Do I dodge everything? 
Should I get enough block to be unhittable? 
Should I still stack mastery after 77.4% block? 
So should I save Shield Block and use it as a major cooldown, or should I use it as often as possible? 
Why is hit rating good? 
Why is expertise rating good? 
Should I cap hit and expertise or should I not? Everybody says different things! 
What's a good abilitiy prioritization/usage for a Protection Warrior? 
Damage dealers are pulling aggro off me early on, can I generate more burst threat? 
Recklessness on the pull? Are you insane? I suffer 20% more damage with it up! 
I heard some Warriors taunt as they pull a boss, why are they doing this? 
Sometimes damage dealers are far above me on my threat meter, why aren't they pulling aggro? 
When/on what kind of encounters is Safeguard viable? 
When should I use Rallying Cry instead of Last stand? 
When is the best time to apply Thunder Clap and Demoralizing Shout? How do I know if somebody else has applied them? 
tip: search in this thread (ctrl + f windows, cmd + f osx) with the numbers within brackets next to the questions.
Q: "Why is stamina good?"
A: Stamina increases your health and is commonly accepted as a primary tanking stat and is rightfully so. Increasing your health increases how many hits you can suffer without dying, it gives your healers much more time to spend casting heals on other players and it increases the odds you come out with healthy amounts of health after suffering a major damage spike.
Take note that increasing your health has no impact on how much damage you suffer - the only secondary gain from a large health pool is a tiny (extremely tiny) increase of overall healing recieved from Blood Craze (if specced into) and Victory Rush. Once your health is high enough for you not to get gibbed (killed very, very fast), many Protection Warriors recommend focusing on decreasing damage taken rather than further increase health.
1 point of stamina increases your health pool by 14 health, but keep in mind we get Sentinel as we chose the Protection tree, increasing our stamina by 15%. There's also Blessing of Kings / Mark of the Wild for another 5% stamina and Plate Specialization for another 5%.
All together, 1 point of stamina is actually 1.25 points of stamina, or 17.5 health.
Q: "Why is armor good?"
A: Armor decreases physical damage taken. While primarily effective vs. melee swings, it also mitigates the effect from non-bleed special physical abilities. Increasing armor is good, but since bonus armor as a stat barely is available to players in T11 (and since it's very weak in it's current form) I won't talk a lot about it.
Q: "What is this 'diminishing returns' or DR thing I've heard of?"
A: Diminishing Returns, DR for short, is referring to how the gain from, value or duration of something diminishes over time, quntity or other factors.
Diminishing returns on avoidance means the more you have of a stat, the less you will gain if you further increase it. If you originally need (NOTE: purely fictional numbers) 50 parry rating to increase your chance to parry by 1%, then eventually you will need 100 parry rating to further increase it by 1%. DR is implemented into the game to prevent tanks from avoiding all too with high end gear or much later on in an expansion. The stats currently subject to DR are parry rating and dodge rating, and since they do similar things, you want to keep both of these ratings at almost equal values to minimize the "loss" to DR.
Q: "Why is parry rating good?"
A: Parry rating increases your chance to parry melee swings made against you. A parried attack reduces the damage by 100%; you completely avoid the damage it would have caused.
A parried attack also procs our talent Hold the Line, but keep in mind since parry is subject to diminishing returns (see above), you do not necessarily want to prioritize parry rating over dodge rating. How much more parry rating you want varies depending on gear and item procs, but generally if you have 20-30% more parry rating than dodge rating you're doing it right.
Your base parry is 5.00%. With ~346 tank gear, you will need roughly 200 parry rating to increase your chance to parry by 1%, but as you reach 1000-2000-ish parry rating you'll need roughly 300 parry rating for another 1% parry.
Q: "Why is dodge rating good?"
A: Dodge rating increases your chance to dodge melee swings made against you. A dodged attack reduces the damage by 100%, just like parry would.
Your base dodge is 4.05%. With ~346 tank gear, you will need roughly 200 dodge rating to increase your chance to parry by 1%, but as you reach 1000-2000-ish dodge rating you'll need roughly 300 dodge rating for another 1% dodge.
Q: "Why is mastery rating good?"
A: Mastery increases your chance to block and critically block melee swings made against you. A block is 30% less damage taken, and if a block occurs you have a chance to critically block. A critical block blocks twice the amount - 60%. For every 179.28 mastery rating you gain 1 point of mastery, and for every 1 point of mastery you gain 1.5% block and 1.5% critical block.
Among all defensive ratings, mastery is particularly unique for two reasons. First and foremost, it covers the attack table at a very rapid rate - roughly three times faster than dodge or parry. This allows us to reach combined avoidance values exceeding 100%, making virtually all attacks against you at least blocks. Secondly, since there is no diminishing returns on mastery and since our mastery increases both chance to block and chance to critically block, mastery has what one can call a reversed diminishing returns (RDR); it becomes stronger the more you cumulate.
Currently, your base mastery is 8 points, your base block is 32% and your base critical block is 12%.
Q: "People say I want different stats or trinkets for different occasions, but how do I know which stats I want?"
A: In most encounters normal stat balancing applies. However, there are circumstances that make certain stats more desirable for an encounter. E.g. in a magic damage heavy fight, since magic damage cannot be blocked or avoided, stamina is a preferred stat, or a way to mitigate magic damage through resistance. This is why, prior to gaining the Mirror of Broken Images trinket, protection warriors were recommended to stack extra stamina for the Nefarian encounter because of the big hit from Nef's electrocute ability.
Another example is the Chimaeron encounter, whom in last phase begins to hit too hard for normal mitigation (via block) to be very effective, thus tanks would switch to extra avoidance in hopes to avoid few extra attacks before getting killed, giving the raid time to finish the encounter. It is the function of the tank to be aware of the boss mechanics, so he / she can switch to an appropriate trinket of choice.
Q: "What talents for survivability do I want?"
A: Must have survivability talents for protection warriors are, beginning from the top; [Toughness], [Shield Mastery], [Hold the Line], [Last Stand], and [Bastion of Defense]. From the Arms tree, you should also count [Field Dressing]. Optional and situational talents include [Impending Victory] (should always be accompanied by the Glyph of Victory Rush), [Safeguard], and [Blood Craze]. None of the last three are a must-have, however.
Q: "What is this 'unhittability' I've heard about? Do I dodge everything?"
A: "Unhittable" is a state when your miss, dodge, parry, and block cover the entire combat table, pushing normal hits of the table. The easiest way to determine that is to add all your stats together; dodge-% + parry-% + block-% + 5% standard miss chance (7% if you're a Night Elf). Once that number reaches 102.4% you have successfully removed normal hits from the combat table and every physical hit that you suffer is either avoided or blocked, every time. The term unhittable does not refer to avoiding every hit but for the lack of normal hits.
Q: "That sounds cool, so I should get enough block to be unhittable?"
A: Yes and no. Warriors cannot get to 102.4% without really fancy BiS hard mode gear and even then it is partially DPS gear. Start-up warriors should aim to reach 77.4% as soon as possible, because at that point using Shield Block (+25% block) will put you to 102.4% for 10 seconds, making it a reliable tanking CD.
Q: "Right... well I probably won't get gear that fancy, should I still stack mastery after 77.4%?"
A: Yes, because a) any excess block from Shield Block, beyond a 100%, is converted to critical block, b) your survivability, when shield block is not active, still depends heavily on your ability to block as many attacks as possible, and finally c) because when you have really high block, trinket functions like that of Porcelain Crab and Vial of Stolen Memories will also allow you to, temporarily, reach unhittable.
Q: "So should I save Shield Block and use it as a major cooldown, or should I use it as often as possible?"
A: As with many other things, it depends. Shield Block is an ability that triggers lots of effects; there's the threat boost from Heavy Repercussions, the bonus block and crit block for physical damage and the -20% magical damage taken. The common approach is to use it as often as possible, unless the boss is going to have a long downtime or you're going to need it for a specific purpose like bursting threat or decreasing a major magical damage spike.
For instance, when tanking either Nefarian or Onyxia, it's recommended to utilize the decreased magical damage taken as well as possible. Try to line it up to cover a breath attack, but don't bother waiting if Shield Block comes of CD right after a breath was performed.
Q: "Why is hit rating good?"
A: Hit rating increases your chance to hit with all abilities. Versus a boss (considered level 88) your base chance to miss is 8%. For every 120.109 hit rating, your chance to hit increases by 1%.
Hit is particularly useful for ensuring that your debuffs never miss, and capping hit can work wonders for picking up freshly spawned mobs. If you're interested in increasing pure TPS, however, expertise may be a better option.
Q: "Why is expertise rating good?"
A: Expertise rating increases your expertise, decreasing the risk your attacks are parried or dodged. Take note that your abilities Demoralizing Shout, Thunder Clap, Piercing Howl, Heroic Throw and Shockwave cannot be parried or dodged but can miss.
For every 120.109 expertise rating, your chance not to be parried or dodged increases by 1% each. For this reason, one could say expertise is roughly twice as good at generating more threat than hit up to the softcap of 26 expertise (6.5%) where your attacks cannot be dodged. Past 26 expertise, you still increase your chance not to be parried up to 14% is covered (56 expertise).
Q: "Should I cap hit and expertise or should I not? Everybody says different things!"
A: No, investing valuable stats on hit and expertise is a waste because Vengeance is so powerful. First of all, hit rating and expertise only decrease the chance of your attacks missing and getting dodged / parried. They do not remove them completely. Secondly, 30-40 seconds into an encounter, Vengeance will have stacked high enough to make any misses meaningless. The amount of attack power you receive from Vengeance, coupled with 300% threat boost from Defensive Stance, will allow you to generate TPS that no damage dealer can match. It means that the first 30 seconds of the fight can be dicy but with proper pulling and team work, it should not be a problem.
There in exception to the rule however, when running 5-man content, where your Vengeance is often in a limbo, going up and down between every trash pack and even boss not being able to provide you with full Vengeance. In such cases, it is perfectly acceptable (if you experience difficulties in maintaining threat) to put on some extra expertise and hit rating, just to make your pulls and burst more reliable, allowing for a more smooth run. Just keep in mind that, in such a case, you are sacrificing survivability to increase your threat and should only do so if you are confident in your abilities, and that of your group.
It is also worth considering hit rating when facing off many mobs at once. Missing Rend can be crucial for your opening AoE threat, missing Demoralizing Shouts or Thunder Claps will also increase your overall damage taken.
Q: "What's a good abilitiy prioritization/usage for a Protection Warrior?"
A: To maximize threat output, I'd suggest an ability prioritization based around our talent Sword & Board, essentially the "Sword & Board-rotation". With Shield Slam as the obvious number one ability, we want to use either Revenge or Devastate as soon as Shield Slam is on cooldown, where Revenge is the stronger of the two. Shield Slam has a 6 second cooldown, so there's three global cooldowns to fill before the cooldown has resetted naturally.
In practice, this means you'll do a Shield Slam > Revenge > Devastate > Something else* > Shield Slam. Whenever Sword & Board procs you'd immediately use Shield Slam and then start over again.
* Something else: there are plenty of choices. This is the ideal time to refresh either Demoralizing Shout or Thunder Clap, this is also when you want to use other high threat abilities like Shockwave (a hard hitter which cannot be dodged or parried), Heroic Throw (also cannot be dodged or parried, plus a 50% bonus threat modifier), Rend (although only slightly stronger than Devastate if a Bleed damage debuff is present) or Concussion Blow (with a 100% bonus threat modifier).
Obviously, also make sure never to drain your rage with Heroic Strike, but don't forget to use it either. It's a button that in most cases can - and should - practically be spammed.
If you do these things but still have issues keeping aggro, then you may want to reevaluate your spec to contain key offensive talents like Heavy Repercussions, Incite, Cruelty or War Academy.
Should neither an improvement of ability usage nor a change of talents make a notable increase in threat generation, you may want to look into increasing your toon's offensive stats. Expertise is the per point of rating, for a tank, highest dps increasing stat. While difficult making a direct comparison, it could be estimated to roughly twice the tps increase over what increasing hit would do, although hit is not to be frowned upon either.
And last but not least, always remember to use Intervene as often as possible.
Q: "Damage dealers are pulling aggro off me early on, can I generate more burst threat?"
A: Yes, there are a lot of abilities and tricks that you can use to generate more burst threat. Make sure you have the [Heavy Repercussions] talent and use the following pre-pull routine; Berserker Stance - Recklessness - Defensive Stance. Also pre-pot with a Golemblood Potion. If you have e.g. a priest in the group, you can opt to use Battle Shout instead of Command Shout, and when you pull make sure you Shield Block - Charge - Heroic Throw - Shield Slam immediately. Like Heroic Throw, Concussive Blow is a high threat ability so you can use it right after Shield Slam, before you begin your normal rotation. Raid bosses cannot be stunned but the damage and threat are still applied.
Using Inner Rage also lets you spam Heroic Strike, so using it on pulls is a good idea. To make sure your TPS suffers as little as possible, use Demoralizing Shout alongside Heroic Strike, when Shield Slam and Revenge are both on CD. Do not worry about Sunder Armor stacks. They will stack naturally as you follow your rotation. Also do be concerned over taking extra damage from Recklessness; your Shield Block will cancel it out. Any hunters and rogues in your group, should ofc use Misdirections and Tricks of the Trade on you during pulls. The threat from those abilities, however, fades after 30 seconds so it is still important to maximize your own threat during that 30 seconds.
Another trick is to use a strength trinket, like Impatience of Youth and macro the use function to your Shield Block. This works well, particularly for tanks who have invested heavily on mastery because the trinket has a lot of it. You will miss a more survival oriented proc or use function but even starting out doing hard modes, I have not found this to be a problem.
Q: "Recklessness on the pull? Are you insane? I suffer 20% more damage with it up!"
A: While it is a shame we have to suffer more damage, the increase of burst threat is extreme. Using Recklessness on the pull allows your damage dealers to freely dps earlier on, it also allows to to perform reliable pulls without having to sacrifice defensive rating points. Not to mention, as you pull a boss, you usually have Shield Block up completely covering for the additional damage taken, and your healers are all at full mana with nothing else to heal.
Q: "I heard some Warriors taunt as they pull a boss, why are they doing this?"
A: Because taunt uses a fixate mechanic, which makes the boss attack only you, regardless of your threat level, for the next three seconds. This is a good precaution for if your first couple attacks miss or get dodged / parried. A DPS, with short ramp up time, can easily pull aggro off you at that time and die. However, if the boss has fixate on him, you have time to use Challenging Shout and hit him with more globals to maintain aggro.
It's not necessarily recommended to do this, but it is incredibly helpful in a few scenarios.
Q: "Sometimes damage dealers are far above me on my threat meter, why aren't they pulling aggro?
A: Because you don't steal aggro when you pass 100% threat; you steal aggro when you pass 110% threat and in melee range, or 120% threat and outside of melee range.
Knowing this is great, because if you spot a damage dealer far above you on threat, completely drop your rotation, wait for him to pull aggro and instantly taunt and then burst out all threat you held back with. This way you'll gain those 10% threat he exceeded yours with for free, set a new threshold and benefit from the abilities you wouldn't have otherwise. If you're fast enough, the damage dealer pulling aggro is extremely unlikely to ever suffer a melee swing.
Q: "When/on what kind of encounters is Safeguard viable?"
A: Any time that a fellow tank or raid member is taking considerable damage. E.g. on Magmaw, MT just prior to mangle, on Omnotron, person focused by Magmatron's Acquiring Target ability, any player during Atramedes' Searing Flame, Cho'gall during Flame empowerment etc. Surprisingly, there are a lot of niches for Safeguard and only comes down to reaction time and making sure it does not compromise the raid, due to being out of position or significantly lowering a tank's threat. Look around and you'll find many places to make use of it.
Q: "When should I use Rallying Cry instead of Last stand?"
A: There is a couple of easy enough rules governing the use of Rallying Cry. Rallying Cry only provides 20% extra hp for 10 seconds. That means that the extra hp must somehow be useful during that duration. If they aren't, then the buff was wasted. Either the buff has to prevent someone from dying, due to hp loss, or make it less likely to happen, in case of more random damage. The buff must also be useful for majority of the raid; using it just for 1-2 people is not useful. Last but not least, using Rallying Cry should never cost a tank his survivability, so he or she must be prepared to get by comfortably without Last Stand, which provides a much more powerful buff.
Good examples of usage are Blackout during the Valiona & Theralion encounter, Searing Flame on Atramedes, Electrocute on Nefarian, etc.
Q: "When is the best time to apply Thunder Clap and Demoralizing Shout? How do I know if somebody else has applied them?"
A: Assuming you follow the S&B-rotation suggested above, the absolute best time to apply these debuffs is on the "Something else"-slot. Keep in mind, however, that once you've built sufficient threat you most commonly focus purely on survival and should as of such interrupt your offensive rotation should either of the debuffs fail to apply, fall off or similar.
To track if these debuffs are up or not, get a debuff tracking addon, and/or similar debuffs together. Remember which other classes have these debuffs. All tanks have both of them; Paladins will apply it passively with their regular rotation, Death Knights will apply them passively with their diseases, and Druids have to manually cast demoralizing roar, while the attack speed debuff is applied with their Mangle and Maul abilities. Some Hunter pets can also apply those debuffs, such as the Tallstrider or the Fox (attack speed), and Bear or Birds (attack power).
Here is a list of all debuffs:
Attack speed debuff:
- Frost Fever (Death Knight - also dps Death Knights)
- Judgements of the Just (Paladin)
- Infected Wounds (Druid)
- Thunderclap (Warrior)
- Earth Shock (Enhance Shamans)
- Tail Spin (fox Hunter pet)
- Dust Cloud (tallstrider Hunter pet)
Physical damage debuff:
- Scarlet Fever (Death Knight)
- Vindication (Paladin)
- Demoralizing Roar (Druid and bear Bunter pet, same ability name)
- Demoralizing Shout (Warrior)
- Demoralizing Screech (carrion bird/vulture hunter pet, normal birds are "birds of prey", they have disarm instead)
- Curse of Weakness (Warlock)
A great way to track them is by using either Power Auras Classic or WeakAuras. Both of these addons allow you to track and display these debuffs in many ways. I can personally recommend tracking them with the inverted logic, in which case you make a list for the debuffs and make the addon display an icon if either of these debuffs isn't on the target.
I have created auras with these functions for both addons. Use their Import-functions to import the auras.
WeakAuras -10% physical damage: http://pastebin.com/raw.php?i=xWz0EE1W
WeakAuras -20% attack speed: http://pastebin.com/raw.php?i=V2ED5Jxx
Power Auras -10% physical damage: http://pastebin.com/raw.php?i=ZP9btwb8 (I cannot confirm if these work as they should as I write this, made them a while back)
Power Auras -20% attack speed: http://pastebin.com/raw.php?i=UPTG25EV (I cannot confirm if these work as they should as I write this, made them a while back)