[ I just made this compilation of useful tips for tanking the first bosses in Icecrown. When I posted it on the guild forum, I thought perhaps it would be convenient to post it here as well. I realise most of it has been said already, and I won't be repeating the general strategy. It's more of a list of little tricks to refine your play. I hope it's useful to someone. Comments are most welcome of course.]

Hints for tanking in Icecrown Citadel: Lower Spire (10-man normal)

Lord Marrowgar

For Lord Marrowgar, the most obvious thing is of course to stand on the other tank. As an offtank, this means sticking to the main tank as much as you can. This is especially important for the start of the fight, so as an off-tank you should stand on top of the main tank before the pull. On the other hand, the main tank must make it very clear when he is going to pull, to give his offtanks the time to react. During Bonestorms, make sure you follow the other tank and run into position during his last storm.

Do not hesitate to taunt after the Bonestorm, even if you are an offtank. You can withstand the damage a lot better than any dps and your healers will generally have no problem keeping you up since they expect steady damage on you anyway. So look for the Bonestorm timer, run in in time and make sure you taunt Marrowgar as soon as possible.

If, for any reason, you don't manage to position Marrowgar correctly (due to an unlucky Bonestorm far away for example), try to shift your character step by step until you've rotated the boss in the right direction. Do this slowly but steadily, and if possible communicate this with the other tanks.

Lady Deathwhisper

Another obvious first rule: pick up the adds as soon as you can. Make sure you have resources and important abilities ready, the first seconds are generally the most important. Try to keep the adds together, this way the melee can use their AoE moves and don't have to move too much in between adds. Make sure you have coordinated with the other tank – a simple rule like “you take left, I go right” makes the adds so much easier.

While the fanatic (melee mob) is usually fairly straightforward to control, the adherents (magic mobs) can prove to be a royal pain. It is important to grab those swiftly and have them all stacked up neatly. Use all the abilities you have to deal with ranged mobs.

When the damage dealers are on the point of breaking Deathwhisper's mana shield, it may be wise to transfer any adds left to one tank. This ensures the other tank is free to pick up the boss while the remaining adds are killed. Taunt off the first tank after 3 stacks, and after that both tanks should just wait for their debuff to fall off. If you can, help interrupting the frostbolts.

Gunship Battle

For this fight, both tank roles are dramatically different. While one is on the same spot most of the time, but always in combat, the other tank is finding himself regularly unoccopied, but has to jump to the other ship and back at the correct time.

The tank who stays at your deck should have a fairly easy time, just make sure to pick up any adds that land. It may be beneficial to pick the tank best suited for area of effect tanking for this role, since the other will be tanking only a single target. Since the mobs that come through the portal grow stronger after time, kill the oldest mobs first.

The other tank should be comfortable with the rocket pack and his camera. It is convenient to bind the rocket shirt to a keybind (Shift-Space works great) to lift off quickly. Regardless of how your guild handles healing assignments (jumping or not), it is probably a good idea to tank the enemy leader on the edge of the ship. This makes a quick escape possible, and it also brings you in range of the healers on your own ship (if you go with that tactic, of course). However, when you land on the enemy ship, first run in to the boss. They are known for attacking from range if not engaged in melee. When you have established aggro, drag them back to the side of the ship. Tilt your camera so you can see when your allies take off and wait for them to leave the ship.

Deathbringer Saurfang

Contrary to the other encounters in the Lower Spire, Saurfang is very straightforward to tanks. There is no need to move during the fight, and both tanks should stand on top of each other since they will taunt off of each other, and Saurfang does not have a cleave ability.

Best is to stand at one side of Saurfang while the horribly long introduction event is going on. By doing this, you can pick up Saurfang right away, and facing him sideways will make sure one blood beast will spawn near the ranged and one farther away. This way, it is obvious which add to burn down and which one to kite, stun or control in another manner.

Make sure you are given a warning when Rune of Blood is applied on the other tank, for example by configuring Deadly Boss Mods. Most of the fight is beyond your control, and disabling the display of warning irrelevant to you, the other warnings become more efficient.

Once you get comfortable with Saurfang, you can use taunt to help out a ranged in trouble with a blood beast. This will essentially double their dps time on the add. However, make sure you will not have to use your taunt again to taunt Saurfang, so watch for the Rune of Blood cooldown.

To slow down the stacking of Saurfang's blood power, wearing avoidance gear (and notably trinkets) is great. He doesn't hit very hard, so losing some Effective Health should not be detrimental. Cooldowns (and certainly avoidance cooldowns) should be used while Saurfang is high on stacks, since at this moment the strain on the healers is the greatest.

[Edited to make clear this is for the 10-man normal version]