Cooldowns, crowd control and you
Tanking is about two things: staying alive and keeping other people alive. You stay alive by gearing properly (mastery, dodge and parry, in that order) and learning to manage your cooldown abilities. For a protection warrior, those cooldowns are Shield Block (1-minute cooldown untalented, 30 seconds with full Shield Mastery), Shield Wall (5 minutes, also modified by Shield Mastery down to 2 minutes, glyphable to increase the duration by 2 minutes but increase the effect by 20%), and Last Stand (a talented 3-minute cooldown adding 30% extra life for 20 seconds). Rallying Cry is a group- or raid-wide cooldown all warriors possess; it cannot be used with your own Last Stand, but another warrior can use it at the same time you use Last Stand and it will stack.
Of these cooldowns, Shield Wall should be reserved for use when you know a boss is going to hit you very, very hard or when you seem to be on the verge of death, while Shield Block is useful pretty much on cooldown. That is to say, if you can use Shield Block, you probably should, as long as the things you are tanking are actually in a position to hit you. Don't hit Shield Block if you plan on Heroic Leaping away from what you are tanking immediately after. Do hit Shield Block if you plan on Heroic Leaping into a pack of mobs immediately after.
Due to the interaction between Last Stand and Rallying Cry, some warriors choose not to take LS and simply use Rally as their life cooldown. I personally prefer to have both. If you have both, use Last Stand when you know you'll take a lot of damage and Shield Wall isn't available, instead of Shield Wall when you believe your healers can manage to heal the extra life and just want to ensure survival, or again if you believe you're going to die. In this case, Rally is best serving your group for situations when your entire group is about to take a big hit.
Saying a cooldown is best saved for a situation does not mean you should never use it. Cooldown durations have been heavily reduced for all tanking cooldowns over the years. With Shield Wall at 2 minutes fully talented and unglyphed and Last Stand at 3, you can use these cooldowns proactively during trash and still most likely have them up during boss fights. One of the things that makes tanking easier is gauging your healer's likely mana needs and using these cooldowns to make things easier. If you are being healed by someone in heroic Dragon Soul gear through heroic Deadmines, you can probably hold onto your cooldowns. Likewise, if you happen to be in full heroic DS gear in heroic Shadowfang Keep. But if both you and your healer are barely geared enough to run normal Lost City of the Tol'vir, use those cooldowns on trash pulls. Don't just expect your healer to keep you up through a six-pull with no CC; help him or her out.
By the way, I know everyone says you don't need CC anymore. Use some common sense here. If your group is all wildly overgeared for an instance, sure, AoE away. If you're in greens, by all means use CC. It doesn't even pull to CC mobs anymore, so the DPS can merrily sheep, Sap, Repent, Hex and Root to their heart's content. Trap 'em, shackle 'em, whatever works. Don't let concerns about the pace of the dungeon blind you to your own capabilities. If you can chain pull and the healer and you aren't even blinking, great -- but if that's a bad idea, don't let yourself fall into that trap.
What to do in combat
Generally, tanking warriors have a single-target rotation and a group/AoE rotation. (Priority system might be a better term to use than rotation.) We'll discuss both. While the threat and Vengeance changes recently implemented do make threat much easier to maintain, warriors generally have two windows wherein threat generation is most important. These windows are roughly 5 to 10 seconds into an initial pull and any time new adds/mobs enter into an already existing fight situation.
In most 5-mans, if you're going to tank several adds and aren't using CC, warriors can charge or Heroic Leap into a pack. This is best done with a short-duration cooldown like Shield Block to ensure that initial damage isn't too spiky, depending on your gear. If you know there's a caster in that pack, Spell Reflection and/or Heroic Throw with the Gag Order talent can also be helpful. If you and your group are comfortable with each other, this tactic can be used with CC -- simply have the mobs crowd controlled after you have initial aggro on them. For most PUGs, this isn't advised, but done properly it's very effective.
If you're Heroic Leaping, the initial aggro caused by the attack's AoE damage will allow you to hit Rend on a mob and immediately Thunder Clap to spread the bleed via Blood and Thunder (assuming you have this talent). If you either don't have the talent or are charge pulling, hit Thunder Clap immediately and follow it with a Shockwave as quickly as possible. You should be attempting to stack the Thunderstruck buff if you have that talent by using TC and Shockwave together. Blood and Thunder is an extremely strong tanking talent for AoE situations. If you expect to be doing a significant amount of trash/AoE tanking, you should definitely take it.
Also, the arms cooldown Retaliation is now a solid move for AoE tanking. With its 5-minute cooldown, you're not going to be using it on every trash pull, but popping it just after hitting a Thunder Clap when you've snagged initial aggro can definitely help smooth out that initial period where threat is hardest to maintain. Use Cleave and then the usual Shield Slam/Revenge/Devastate to help maintain threat, in roughly that order. Use Revenge over Shield Slam in AoE tanking situations if you have Improved Revenge.
For single target fights, you'll use TC primarily only to debuff the boss' attack speed and Demoralizing Shout to reduce its attack power. You'll only use these to refresh their durations or to refresh Rend if you have B&T in your tank kit. Otherwise, you'll use Shield Slam as your primary threat move (pair with Shield Block if you have Heavy Repercussions), with Revenge as your next highest-threat move, and Devastate to keep Sunder up on your target. Rend is useful to keep damage ticking on a boss but not as important as it is for AoE tanking. Heroic Strike will be used as your rage dump, paired with Inner Rage if you find yourself absolutely swimming in rage and want to burn it off. Shield Slam > Revenge > Devastate, then use other abilities like HS or TC/Demo to fill in the gaps or bleed off excess rage.
Some basics to keep in mind:
Survival trumps threat. In most cases, you can taunt a mob or boss back, but you can't do anything if you're dead. Don't tunnel vision on your rotation and forget to use a survival cooldown if you're going to die.
The healer is the most important person to save in a group. If things go south and a DPSer and the healer both get aggro, save the healer first.
The DPSers are not unimportant. You can't kill anything with dead DPS. Unless a DPS player is being problematic, it's your job to keep threat off of them as well.
Be hitting buttons. Don't try and tank passively, sitting there auto-attacking. You wouldn't DPS that way -- don't tank that way. If you don't need to use a cooldown, use an offensive ability. You're a part of the group, not a prop they hide behind. Get in there and hit something.
Next week, I'll be trying fury out again and seeing if better gear starts to compensate.
At the center of the fury of battle stand the warriors: protection, arms and fury. Check out more strategies and tips especially for warriors, including Cataclysm 101 for DPS warriors, a guide to new reputation gear for warriors, and a look back at six years of warrior trends.