DW Frost Tank

It's a pretty straight forward build.

The rotation for this tanking is rather simple. and can be calculated into 3 5 second counts.
1 (1-5) D&D
2 (5-10) Icy Touch, Plague Strike, Pestilence
3 (10-15) Howling Blast, Blood Boil

As long as you have your Defense capped (so you won't be crited), your Expertise capped (so you won't let anything parry your MH, OH, or Specials), and your Hit at 9% (you won't miss on any specials). The reason why I say a 5 second count is for flowing reasons. You will always have your blood runes on CD, and you will be able to continue your grind forever throwing in Rune Strikes, and Frost Strikes in between each count helps.

The reason why it's DWing is due to the majority of your moves aren't based on weapon damage, but rather AP.

Obliterate is in there for single target tanking. While yes it is based off of weapon damage. It still does more with a slow MH then Howling Blast will ever do. This allows you to tank bosses easier, and it also works well with single pulls.

A few questionable mentions for the build are.
1) No Blood of the North - Who needs death runes when your continuously using blood runes.
2) Hungering Cold - Add it to your OH SHIT button as most of your defensive spells don't use a GCD.
3) Virulence/Nerves of Cold Steel - 3% Hit is hard to pass up in a raid.
4) 2 points in Anticipation - Your main defense is parry not dodge. Focus on what you do best.
5) Deathchill - No GCD. Place it on a Howling Blast Macro and crit everything around you.
6) Bladed Armor - Your a tank. If you don't have this you fail as defense = AP, and AP = damage, and damage = threat.