Blizzard said that they don't want heroics to be another aoe fest like LK was, but this is not the case.
Except for 2-3 pulls in some instances, you can aoe tank everything without having to wait for the healer to mana up afterwards - granted both needs some HC gear.
Ofcourse you can't just thunderclap, cleave and sit back and relax though...
Preferable group composition: 2 Ranged dps, 1 Melee.
Melee DPS takes a lot more damage than ranged which taps the healer dry way faster than if there weren't any. Once your healer is decently geared and using the proper mana efficient spells it's not a problem. (Druids spamming Rejuve like the old days will find themselves Oom very quickly)
Prot Warrior tank specific:
Mark the Caster mob (especially healer) with Skull.
Pull the caster with a Heroic (silencing) Throw and charge immediately.
If: DPS and the healer can keep it in their pants for 1 second, apply Rend then Thunderclap.
If not, then Thunderclap (sometimes a mob might have moved behind you, making shockwave fail)
Turn so you face all / most of them and shockwave, Concussion Blow (5 sec stun) the skull.
Cleave and apply 1x rend on any mob then Thunderclap again.
Disarm a Melee mob & Shieldblock [Keep it on CD ofcourse]
Hoofstomp if you're tauren [Most likely interrupting a mob cast, or save it until you see a cast]
Taunt the skull (most likely needed by this time)
Target a caster mob and interrupt
Demoshout
Keep Shockwave, Disarm, Conc Blow, TC all on CD.
If HP drops to 60% use a trinket, if HP drops to 45% use Enraged Regen
If you see you're taking a savage beating, Heroic Leap away, DPS can still keep on nuking - you can taunt from range.
Charge back in stunning & interrupting a mob when the Healer has managed to catch up.
On very large, hard pulls blow Shield Wall after your Shockwave stun wore off earlier. Don't save your CDs for a rainy day, use them - most of them will be ready for the next tough group.
Many mobs move fairly slowly and can be kited. Use it to reduce damage taken. Most DPS classes can slow mobs heavily, so after you've build some fair aggro simply leap away and wait for them to kill it - taunting and Heroic Throwing if they get close on threat. If they finally catch up to you and taunt is on CD, either have Vigilance on the top dps, so you can just keep on taunting or charge (stun) in and resume tanking as normal. This is ofcourse not needed often, but works well on the 2x Oaf pack in Deadmines that can really wallop a tank - so that only one is hitting you at a time.
Prio Mastery and Parry for your Prot Warrior.
Interrupts is key to damage reduction. Doing +30 interrupts as a tank in a HC is normal.
Especially your Melee DPS' #1 Prio is to interrupt, then DPS. There is not a single reason not to interrupt, infact it's a DPS buff for a DPS Warrior to Interrupt (5% dmg bonus for 30secs if talented)
Hope it helps someone.
Then I won't need to worry about keeping the tanks in randoms happy so that they (who think they do the world a huge favour) won't leave the group...