So since I have tanked all existing content as Frost (the spec people claim is the tanking spec) I thought I'd stray away from the herd a bit, and do it all as Unholy.

So far in heroic dungeons my AOE threat is insane. Much higher than when I was Frost even with Deathchilled Howling Blasts. The flexibility to be able to drop a Death and Decay every 15 seconds is very nice. The DPSers all say this is their favorite of my tanking specs so far. This is a very potent AOE spec.

I did Naxx10 with this spec last night, and was noticing a lot on bosses where only one thing is hitting me that Bone Armor was sometimes staying up for 30-40 seconds before the 5th charge was expended. That's 30-40 seconds of 40% mitigation from everything because my avoidance is so high that the charges just don't get expended.

We also did Sartharion with Tenebron up. He's the drake with the eggs in the Shadow Realm. I was able to pick up all of the drakes instantly, and do significant damage to them. In fact, for the fight I was top DPS with 3998 DPS because I was AOEing the ENTIRE fight. When I was using Pestilence on the packs of fire elementals or drakes it was hitting Tenebron and Sartharion as well. I am assuming that it was a product of large dragon hit boxes and the Glyph of Pestilence.

As far as playstyle I think that this is my favorite spec. When I was frost I was still opening pulls with Death and Decay, but I felt like DnD was competing with Howling Blast. I don't have to worry about that anymore. I'll give this spec some more time, and do some more heroics with it, but honestly this is the most fun tanking spec I've used so far.

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Spec: http://www.wowhead.com/?talent=j0EZ0xZfghc0bogcqMcsut

Glyphs: Death and Decay, Bone Armor, and Scourge Strike