Sansterre

I've long thought that these two talents are overlooked, the former more than the latter. Combined, they achieve mitigation way beyond what can be found in gear. If I'm mislead, I figure here's the place to find it out. Here's my reasoning (with math in parenthesis.)

Let's take a tank with 55% armor mitigation and 44.4% dodge + miss + parry. This combines rather neatly for the tank to be taking 25% of the raw damage the mob is lobbing at him.

With normal demo shout and normal thunderclap on, the tank should take only 18% unmodified damage. (.25 [normal damage] * .9 [1 - the effect of a 10% attack speed reduction] * .8 [1 - general approximation of demo shout's effect, 20%]). This is a 28% reduction in damage taken from normal.

But with improved demo shout and improved thunderclap on, the tank should only take 14% unmodified damage, which is a 44% reduction from attacks without the debuffs, and a 22% reduction from attacks with the unimproved debuffs. (.25 [normal damage] * .8 [Improved Thunder Clap reduces attack speed by 20%] * .7 [Improved demo shout increases demo shout effectiveness by 50%].

These are not small reductions - they are enormous. But, one might argue, that's what gear is for. Why spend points on these specs when gear can handle mitigation for us?

Let us say that the tank in question is cautious, always putting up demo shout and thunder clap. With these, as mentioned above, the tank is taking 18% normal damage. He wants the mitigation afforded by the improved talents (14%), but is unwilling to spec for it, and will make up the difference in gear. The difference in gear required to reduce an 18% incoming damage to a 14% is rather severe: 95 defense, or 220 defense rating. Or, put another way, 12.3% dodge + parry + miss. (Math Below). That is a pretty freaking gigantic amount of gear required to make up the difference.

In terms of speccing, that is 8 talent points for 100 defense or 12.3% DPM. Other talents include 1 talent point for 4 defense (compared to 12.5) or 1 talent point for 1% parry (compared to 1.5). So, in short, Improved Demo Shout and Improved Thunder Clap may be the most, or at least among the most, efficient talent point investments for mitigation.

A side thought is that if the 18% damage taken is acceptable for the encounter (non-improved) then the tank with improved talents is in a position to shed 100 defense or so for a comparable amount of stamina or threat (hit + crit) to enhance his performance.

*Disclaimer*

The above is reasonably accurate, as far as I can tell, but it applies specifically to *white* damage. Thunderclap will only mitigate white damage, and demo shout will only mitigate white and certain special attacks. So depending on the situations you find yourself in, the above may be valuable or trash. If you're tanking Illhoof - 50% of your damage taken is shadow, so these talents don't matter much. If you're tanking the prince, especially Phase 2 where the game is keeping up with his white damage, it's a godsend. So take the above for what it's worth.

*Math*

The gear to talent ratio thing. Basically, you have to move 18% to 14%. To get that you would need to get an armor mitigation * avoidance amount of 80.56%. (14% [desired reduction] = 72% [effect from 10% thunder clap times 20% demo shout] * x [amount taken after armor * avoidance]. This makes .1944 (which gives us the 80.56% number).

So armor amount taken is 45% and avoidance taken is 55.56%. Each point of defense is worth .04% parry, dodge, miss and block. For sake of illustration, let's make 1% block = .25% parry. So each defense = .13% mitigation. So the formula of defense needed to achieve A&A of 19.44% taken is:
0.45*(5/9-D*0.0013) = .1944
Jiggle that formula and it should come out to D = 94.97 defense, or 220 defense rating. If you take the formula and replace '.0013' with '.01' then you can solve for the amount of dodge+parry+miss [DPM] that it's worth.

If my math is off at all, let me know.