As a raiding kitty gears up through Icecrown Citadel and the following hard modes, he or she is likely to start pushing several different stat caps that currently limit certain statistics. Some of these caps are more important than others, and some of them are related to others in the way that you gear for them. The stat caps that you’ll want to worry about are:
The Armor Penetration Cap: At 1400 armor penetration, you reach the hard cap of 100% armor reduction. Any armor penetration beyond that is worthless. It’s good to still look for pieces of gear with armor pen on them, however gemming will need to be adjusted accordingly so you’re not over this cap by much. Usually it is good to switch an armor pen gem to an agility one if it will take you over 1410 armor penetration. At that point the agility gained is worth being slightly under the cap, as opposed to half of the stats from an ARP gem being completely wasted.
The Critical Strike Cap: This is much different from the Armor penetration cap. As your agility increases, so will your critical strike chance. Once your critical strike chance hits 73.3% all your auto attacks (your white damage) will either crit or be glancing blows, as there is a flat 29% glancing blow chance for all white attacks. At this point, critical strike chance loses value, and hit and expertise gain more value, as the more white attacks that land, the more crits there will be. Keep in mind when trying to figure out your crit chance raid-buffed to count in procs and buffs from items such as your idol, or your trinkets. It can be helpful to use a tool such as Rawr to figure out how the uptimes from said items will affect your crit chance.
The Hit Cap: While generally not a very valuable stat to use at lower levels of gearing (a cat druid’s dps has a comparatively low contribution from white damage), when a cat is pushing the critical strike cap, it becomes almost essential to also be at the hit cap. As one approaches the crit cap, white damage percentage goes up to a point that hit capping is something you definitely want to do. Try to do this through as few gems as possible (especially if you would go below the ARP cap) through the use of hit enchants, to get to the cap of 8% hit. If you’re alliance, DEFINITELY only gear to 7% hit rating, and make sure you run with a draenei in your group.
The Expertise Cap: Similar to the hit cap, this stat reduces the chance that a boss has to dodge you when you dps it from behind, and this stat gains importance as the crit cap is attained for the same reason that hit rating does. The cap melee concern themselves with is 26 expertise, or 214 expertise rating. This is another cap that you want to reach through as much passive gearing as possible, and certainly don’t gem for it until hit and armor pen caps are both attained.
Items and Enchants that greatly affect or are affected by these caps:
The choice between Mongoose and Berserking: As said above, when one approaches the crit cap, the value of crit and agility diminishes. So as you get closer to the crit cap, the value of the Mongoose weapon enchant decreases drastically. Also, the haste given from the mongoose enchant has recently been stealth-nerfed by blizzard, so the haste is no longer a contributing factor. When you get to the point where idol and trinket procs (such as Deathbringer’s Will or Death’s Verdict) will put you at or over the crit cap, it is a good choice to drop the mongoose enchant for berserking.
Hersir’s Greatspear (and it’s heroic version): This is a great weapon to have available to you (especially the heroic version) The armor penetration and hit it provides pretty much guarantee that you’ll be capped for both stats, and it helps simplify gearing and gemming immensely. I’m still currently using the heroic version of this weapon, as heroic 25-man weapons stubbornly refuse to drop. When I finally do get my hands on Heroic Distant Land or Bloodfall, I’ll be somewhat sad to drop this weapon, as it simplifies gearing immensely.
Distant Land and Bloodfall (and their heroic counterparts): While these weapons will always be upgrades due to the feral attack power bonus gain, they do tend to make gearing to the hit and armor penetration caps much more diffcult. Even if you do end up losing several hundred armor pen due to the upgrade, it will still be a dps benifit to you, as you will gain large amounts of agility, feral AP, and haste. The heroic versions of these weapons are also very likely to get you crit capped as well, so make sure to account for that. Distant Land is better than Bloodfall by a hair, due to less stamina and more dps stats.
Lasherweave Legguards (and the two upgrades): These pants are very important, as they have a lot of expertise on them. These will certainly be the first set of tier that you will want to use your marks of sanctification on, as the higher-ilevel versions give even more, and put you pretty close to the expertise cap. This is the best way to passively gear for expertise, and this makes running Ikfirus’s sack of Wonder something you don’t want to do (running a piece of gear with more ArPen is much better).
Enchant Gloves: Precision: This is a nice glove enchant to use once you start pushing the crit cap, especially if you’re still worrying about staying as close as you can to the Armor Pen cap. This would generally be replacing the standard feral glove enchant of +20 agility to gloves. This is the equivilant of switching an epic hit gem for an epic agility gem. This way, you can get an extra 20 hit rating without having to lose 20 armor penetration.
Deathbringer’s Will (and its heroic version): Any good feral knows that this is a must-have for the armor pen and the awesome proc. However, this is still worth mentioning, because it is good to consider that one of the three stats that procs is 600 agility, which provides a lot of crit. Make sure to keep this in mind, as many ferals will be well over the crit cap when the agility option procs.
COMING SOON: Sharpened Twilight Scale: The armor penetration on this trinket is pretty astounding. I don’t know what the exact numbers on this are, but I expect it will become best in slot for ferals along with Deathbringer’s Will. This will also clear up a lot of armor pen issues you’ll have if you’re running with Distant Land or Bloodfall.