Secondary Stats
Boss down! /cheer! And he dropped loot that I can use! Or can I? Do I need Mastery? What's expertise? I lose a lot crit if I use it but get haste and hit. Is it better? Who knows. Trying to figure out what gear is for you can be as strenuous as taking down the boss itself. Below is a list of the secondary stats (the green text on items) and a basic overview of what they do. Also, there are links to some of the class forum threads that tell you what stats you should be getting and why.
Spirit - Spirit affects your mana regeneration in and out of combat. In special cases (shadow priests) spirit can be talented for conversion into hit rating. Spirit is generally only useful for healers (or shadow priests) where mana regeneration becomes very important for long fights. The more spirit you have the higher your mana regeneration is while casting spells.
Hit - Hit is the most important stat for DPS who are getting geared for heroics and raids. Hit rating decreases the chance to miss an enemy, based on what level that enemy is. The higher the level enemy, the more likely you are to miss it. The enemy level is important for determining how much hit rating you need to be 'capped'. Being capped means that you won't see that dreadful 'miss' graphic when you use a spell or attack. Luckily, for heroic bosses you only need to have a hit rating that correlates to 6 percent. For raid bosses it's much harder to be capped (17%). Remember, if you have talents that increase hit by x%, you only need hit rating from gear equal to 6-x%. If you're curious what your hit is, go to your character sheet by pressing 'c'. If you scroll over 'hit' it will display a tooltip with your chance to miss against level 85-88 enemies. All gearing priorities should be based on getting 6% hit. Once you hit that (if you don't plan on raiding), you can aim towards increasing another secondary stat. Also, if you're healing you should never have hit on your gear unless you are upgrading from a very low ilvl and waiting for something to drop.
Mastery - Mastery is the new mechanic in Cataclysm. Mastery gives you a unique passive bonus depending on your class and what spec you choose within that class. Once you reach level 80 and purchase Mastery from your trainer, it will be active at all times. Your best bet is to look up how your Mastery works and whether or not it should be a high priority on gear or not (Resto Shaman do not stack Mastery for example).
Critical Strike - Critical strike improves your chances of doing additional damage or healing. Critical strike additional damage can be anywhere between 100%-200%. The amount of damage you do depends on your class, talents, and meta gem. Depending on your class or play style stacking crit may be to you're liking. It's important to note that crit can be unreliable when healing or DPS'ing where you may string a bunch of spells that don't crit. From a mathematical point of view however, if you cast a large amount of spells, you will always converge on your critical strike chance.
Haste - Haste is my favorite stat in the game. It increases attack/casting speed of your abilities and melee attack and how fast your damage over time spells 'tick' for damage. For classes that use lots of DoTs or HoTs there is usually a haste soft cap to reach to get one extra tick out of your spell. It's not always an ideal stat to have however. For arcane mages, haste is very low on gearing priority mainly because it will make you lose mana too fast to last on boss fights. In other cases, haste doesn't compare to other secondary stats in terms of raw dps numbers or damage mitigation. Haste is tricky like that, so it's best to check your class forums for the answer on how awesome or unawesome it is.
Expertise - Expertise reduces the chance for an enemy to dodge or parry any melee attack. This can be important especially for some tanks because when a boss parries an attack, it gets a free swing that's off of the swing timer. For example, if a boss attacks once every second and parries an attack, it will swing twice in that one second time frame. That means more damage to the tank. Expertise is only useful for melee classes.
Dodge/Parry/Block - I'm lumping these into one to consolidate the list a bit. All of these are damage mitigation stats and should only be used tanks. Parry gives you a chance to deflect a melee attack as long as you are facing the enemy. If you're getting attacked from behind, you can't parry (this is why all melee DPS attack from behind enemies). Unlike parry, dodging doesn't depend on where the enemy is attacking you from (front or back). Also, parried and dodged attacks result in no damage done. Blocking attacks will reduce incoming damage by a base 30%, which can be increased through talents such as Holy Shield or Critical Block. Blocking can only occur if a shield is equipped and block rating increases your chance to block, not how much damage is blocked.
I won't go through Resilience since it's a PvP stat and no one likes PvP. It's important to remember that regardless of your class, Hit is the #1 stat you should be stacking until you reach 6%. After that, you either want to get Mastery, Haste, Expertise, or Crit. To figure out what's best, I've provided links to class guides on the forums. The section you want is usually labeled stats and reforging:
All Mage Specs: http://us.battle.net/wow/en/forum/topic/1648728060
Shadow Priest: http://us.battle.net/wow/en/forum/topic/1764409092
Fury Warrior: http://us.battle.net/wow/en/forum/topic/978197846
Boomkin: http://us.battle.net/wow/en/forum/topic/2721372177
Don't forget, if a piece of gear isn't optimal for your build you can always reforge it!
ryguy












