Illustrating Chill of the Throne
So, for all the talking about it, we've managed not to demonstrate yet why they're using this. Knowledgeable tanks have just been trying to explain to the community about how this is a good thing, but I think I can actually demonstrate why this is a good thing.
Chill of the Throne will make it so that while your dodge chance doesn't actually change, you functionally have 20% less dodge if you're being attacked. Think of it like giving everything in Icecrown Citadel an Expertise aura.
Why are they doing this?
We've heard it said that avoidance is too high, right? But why is it too high?
Two simple values to consider when considering tank damage taken are the size of the hits (how much damage you see pop up each time), and how much damage the tank takes in total (easiest way to represent this within the varying time frame is with incoming dps).
The size of the hits you take is determined only by mitigation, by armor, resistance, block, and passive reductions from stance, talents, and buffs.
The amount of damage you take overall, however, is dependent also on avoidance. In a large enough average, 50% avoidance *is* 50% damage reduction, but that value will vary when you look at smaller sample sizes (i.e. in a 1 min fight you may actually avoid only 40% of the incoming attacks, or you may avoid 60% and get more value out of the avoidance in that small time frame). This overall damage reduction has to be accounted for by Blizzard, though given the random nature of it, I'd bet they value it slightly differently than a direct comparison with armor reduction percentage.
So, let's throw around some more solid numbers to illustrate. Let's consider a fictional boss in tier 9 content. Blizzard wants him to do about 5k dps to the tank (to balance against the expected level of healing the healers can put out, which is in turn a factor of the expected gear level, and level of distraction for encounter mechanics).
If the expected average tank will have 65% reduction from armor, 15% (rough average for the classes) reduction from stance and buffs, and 60% avoidance, the boss will have to do roughly 42k unmitigated dps to result in that 5k dps actual effect.
42k unmitigated dps would, with those stats, result in swings hitting for 84k before mitigation on a 2 sec swing timer, which the tank will see as 25k hits when it lands.
If they then want to step up to the next level of content, we'll say the tank now has expected average values of 67% damage reduction from armor, 15% miscellaneous damage reduction remains unchanged, and they will now have 65% avoidance. Being the next step up in content, they now want the tank to take 6k incoming dps.
Following the same math as above this would be 61k unmitigated dps, or 122k damage per hit before mitigation. With the expected stats that would be 34k per swing.
Ouch right? To keep tank damage stepping up to match improved healer output, and while making the new tank gear an improvement so tanks want to upgrade, the tank is now getting hit much harder. To make that sustainable and not reach a insta-gib threat, the tank's health pool would have to scale much faster, and this is a runaway train.
So, the step they're taking is to reduce avoidance. If you follow this path of balancing however, watch what happens.
The goal is that the tank takes 6k dps. The adjusted stats are 67% from armor, 15% from stance/buffs, and 45% avoidance (note: you will still get the same step up from gear, that hasn't changed).
From these values the boss will have to do 38.9k dps, or 77.8k per swing every 2.0 sec. With these mitigation values, the tank will now take only 21.8k damage per swing.
Note: the incoming damage is the same in overall scale, but each hit will actually be smaller than the previous tier. That means, to healers, you'll still be getting hit harder than ever before in total, but your whole health pool won't be flipping on and off like a light switch to get that increase. What really changed? You will take more hits, but any given hit will be smaller. This means you move away from the danger of "miss a heal and the tank dies" or "the tank took critical damage in less time than it takes to cast a heal because 2 effects lined up at the same time." You still take more damage, more healing is still required, but suddenly the tanking/healing game is fun again, instead of walking a razor's edge between life and death.
Following this path to find the desired balance, you can see why this is the smart move for Blizzard.
Now, it's been written well in many other places, but I'd like to re-emphasize something here. There are a couple of common reactions I've seen to this:
1.) "Why doesn't Blizzard just give us less avoidance?"
In order to do this, they couldn't just give us less on t10 gear, or we'd use t9 and not want the upgrades. They would have to rework all of the tank gear in the game to re-balance this one need. Chill of the Throne is a much simpler stepping stone, and Cataclysm is the time for the global paradigm shift. Expansions allow for the whole outlook to change because they can start semi-fresh, and sweeping changes are easier to implement with the LONG testing window and less mid-stream disruption.
2.) "Why didn't Blizzard see this coming?!?!"
Well, to a degree they did, and they've been trying to make small steps to keep things stable. They mentioned back in Naxx that they've felt avoidance was too high, and it's been seeing little adjustments here and there. Really, it hasn't reached a critical point yet, and I think they could've done Icecrown without really making a big change like this, but this change frees their hands to make a lot more interesting design choices in encounters, rather than trying to play in the corner that was painted. As above, this isn't the time to re-write the expansion, this is just a smart step to keep the balance the same in previous tiers (as they are currently working well enough), and leave us poised for a more flexible balance in Cataclysm.
3.) "Well, if cutting avoidance a little works so well, why don't we just get rid of it all together?!"
The thing is, this is a *balance* that makes the game more interesting. Considering the math above, if you have avoidance too high, the tank is teetering between life and death with every swing because they have to hit really hard when they do land. Alternately, if you take avoidance away completely, the tank just takes a constant and 100% predictable stream of damage. 6k dps with 65% armor rdx and 15% miscellany rdx becomes 20.2k unmitigated dps, and 12k per hit on a 2 sec swing timer. You *will* get hit for 12k every 2 seconds. The healer response to this is, I just find the right size heal and spam it, or I cast my big heal once every other 2 CD's. Suddenly healing no longer requires a brain or reflexes to do. You know what's coming, and there is nothing dynamic about it.
You can add unpredictable elements back in, say, make the tank crittable, or use encounter buffs! But, wait, we have encounter buffs, and to a degree they need to be regular and semi-predictable. That's a big part of what CD's are designed around. Making tanks crittable actually makes a no-avoidance world worse than adding avoidance. Why? Avoidance creates dips, moments where the tank doesn't need healing, which allows for survival, for skin-of-the-teeth luck, etc. It allows the tank to be tank-like and survive. Crits on the other hand mean the tank takes unpredictable surges of damage. Rather than being tank-y, it's now a health risk and a risk to the raid if a crit comes at the wrong time and the healers can't catch it.
Hopefully, this makes some sense to the people who can't get passed the idea that this is a tanking nerf, or a bad thing. Hopefully, you also understand my perspective (which I didn't invent) in the last portion, but this is a forum, this is where we discuss, so, reactions?