Before you try to set a record on any encounter, you should first figure out a few aspects of the encounter as it can greatly affect how you gear/glyph/spec/etc.
Things to consider:
- How much actual tanking will you be doing?
- Will there be lots of AoE?
- Will you be spending more time AoE'ing than doing single target DPS
- Will your vigilance target be taking lots of damage?
Click this to see the basic cookie cutter spec
There are literally hundreds of possible gear/glyph/spec setups you could use, so I won't be covering all of them, and instead will be explaining how I approach a few different generalized encounter styles over the course of the next few days/weeks/centuries.
Spending the entire fight tanking, no Adds, no AoE, Vigilance target takes little/no damage.
On any fight where you are going to have a high amount of shield slam usage, you should be wearing two pieces of the tier 12 tanking set for the bonus damage to shield slam. The ideal pieces to wear are the shoulders and gloves, as they have a lower overall impact on your stat pool than the other pieces.
Any time vigilance doesn't do a whole lot in terms of overall gain in vengeance, it's not a bad idea to just drop vigilance/concussion blow in your spec.
Expertise past 26 is a pretty good idea, but remember it's fairly devalued since it will only affect your chance to be parried, so don't go too crazy stacking it.
Itemize for 8% hit, this should be fairly obvious, but just in case it isn't, now you know!
If the boss has a slow swing timer, or at least anything longer than 2 seconds, I would set up a macro to swap you in to berserker stance, then use Colossus Smash, then switch back to defensive stance. Note that you should time using this macro so that a melee hit doesn't land during the time you are in berserker stance.
The macro should look like this:
#showtooltip Colossus SmashPossible spec/glyph setup:
/cast [stance:3] Colossus Smash; Berserker Stance
/cast defensive stance