You'll find this fight to be almost like the heroic lootship of Firelands; the fight almost gets easier with the changes for the hard mode. Unlike in normal mode, when you kill Rageface and Riplimb, they will resurrect after 30 seconds, so the fight switches from a strategy of burning down the dogs and then killing Shannox to mitigating the dogs' effects on the raid while focusing down Shannox.
Likewise, as a result, you never have to worry about Riplimb dying while you have stacks active and thus can always drop your stacks. Shannox will hurl his spear right up until the end.
The two tanks still need to coordinate, based on who has the job of tanking Shannox and who has the job of tanking Riplimb. The former will be concentrating on keeping Shannox moving intermittently so that melee is never standing in traps of any variation. And the latter while be in charge of camping next to Crystal Prison Traps so as to freeze him every other spear, hopefully allowing both tanks to drop their stacks with regularity.
A helpful tip is to enlist priests to use Leap of Faith to yank tanks away if their assignments get way too close before they can drop stacks. The extra distance should be enough to allow stacks of Jagged Tear or Feeding Frenzy to drop.
Just like normal mode, when the dogs are up as Shannox's health reaches 30% (not that they survive that long on normal, but you get my point), they will both enrage. If you're tanking Riplimb, be sure to have cooldowns ready for that damage spike.
Glyphs I would recommend utilizing Glyph of Focused Shield for sure, since you'll only be tanking one target. The Riplimb tank can also use Glyph of Dazing Shield to slow Riplimb occasionally, but you need to be careful that Dogged Determination won't allow him to be slowed under 50% movement speed, which then increases by 5% until it caps out at 100% and then falls off. Do not using Glyph of Divine Protection, as there isn't much deadly magic damage. Most of the damage is physical.
Loot Shannox carries the heroic leg tier token and the Uncrushable Belt of Fury. I'd avoid Legplates of Frenzied Devotion, as the tier legs are much better.
A fairly simple heroic fight to tank, the difficulty is placed much more on the DPS to beat the enrage timer and for the DPS and healers to handle the hazards of the encounter without dying.
Feel free to shed a tear for the Concentration mechanic, which by virtue of being a tank, you'll never really get to enjoy. You might have a lucky avoidance streak that briefly allows it to stack up to 25%. But don't count on it ever getting past that without some trickery and some animal sacrifice to various deities of fortune.
The way my raid handles the scorpion/cat phases is never allow the raid to each a single Flame Scythe, thus allowing Concentration to stack for each DPS as long as possibe. Three times per fight, I'll use Ardent Defender to cheese a Scythe. The raid then immediately scatters, because Staghelm's energy shoots up to 70% when the Scythe is not properly divided amonst the raid. It'll buy the DPS 4 seconds or so to pour in the hurt, though, which can be quite valuable.
When Searing Seeds are about to go out, you can use Hand of Protection on a melee DPSer to prevent his getting a Seed applied. That'll allow him to do extra DPS by not having to run out and let the Seed explode far away from the rest of other melee players.
As the tank, you can elect to tank a Burning Orb if one pops up in the center the circle where you'll likely be tanking the boss. Swapping off with a melee player is very doable, but be extremely careful not to take too much on your plate in terms of damage.
Loot The heroic shoulder tier token drops from Staghelm, as well as the best-in-slot Bracers of the Fiery Path.
Your biggest focus when tanking this fight will primarily be in doing the required amount of DPS to kill your hatchlings. Unlike normal mode, you'll be tanking three hatchlings (thankfully, one at a time) per "rotation" of the fight. Each, you'll be required to kill quickly before the two Firestorms and Fiery Tornadoes that punctuate the encounter.
The health on the hatchlings is much, much lower, making killing them quickly a very doable task. You should still make an effort to boost your damage output as best you can. This includes glyphs and trinkets (which I'll detail shortly). You can also consider some crazy moves such as combining two pieces of ret tier 12 and two pieces of prot tier 12, as well as utilizing the Ruthless Gladiator's Scaled Gauntlets, to bring an absurd amount of prot DPS to the fight. Truthfully, though, with the recent nerf that will likely not be necessary.
Plump Lava Worm management is similarly key. Their Lava Spew is much more dangerous (possessing a much larger cone of effect) on heroic mode, and you can't chance allowing it to cross your path. Likewise, you really don't want your bird to ever Tantrum for very long, if at all. Watch your hatchling's happiness level, and when it appears that the bird is preparing to throw a Tantrum, quickly feed it a worm. If it does Tantrum, pop a cooldown to mitigate the damage burst.
Glyphs Like Shannox, do not equip Glyph of Divine Protection. You'll be worrying much more about physical damage. Damage glyphs are pretty handy here, instead, especially Glyph of Focused Shield.
Trinkets I'm very fond of maintaining one-trinket block cap for fights like this. Being able to swap out of survivability trinket for the License to Slay and not shoot my survivability in the foot is huge. Keep in mind, though that you only need to boost your hit and expertise relative to a level 87 mob; anything past that is wasteful.
Loot Alysrazor drops the heroic chest tier token, as well as the Lavaworm Legplates (which are threat piece, of course), as well as the Spaulders of Recurring Flames which are a good stand-in when you just can't win that shoulder token to save your life.
The Light and How to Swing It shows paladin tanks how to take on the dark times brought by Cataclysm. Try out our 4 tips for upping your combat table coverage, find out how to increase threat without sacrificing survivability, and learn how to manage the latest version of Holy Shield.