gear & stat management basics
Posted by Ernbrecht in Guides on August 13th, 2010 | No Comments »Gearing up your character, that is to constantly obtain better pieces of equipment, is one of the core principles of the game. But what exactly makes one piece of gear better than another one? With this guide I will attempt to answer that question in depth. I will try to explain how gear works in the game, so that you can answer it yourself. This is going to be a very basic and generalized guide. You will not find a list of absolute numbers here for every spec, class and setup there is (other than some examples, to illustrate a point), to make the best out of this guide, you will still have to research your class.
Part 1: math and mechanics
Every piece of gear has stats on it, and these stats are what we are after – the more stats, the better! The total amount of stats on an item depends on the so-called item budget, which is decided by three factors:
The item level (short ilevel). This is an abstract number that illustrates how high up an item is on the progression scale. For example an item that drops in a Vanilla raid instance (which is level 60 content) will have a lower item level than pretty much any item that drops anywhere in Northrend (level 70+ content), and something from Ulduar will have a lower level than a drop from Icecrown Citadel. Other than the item budget, the ilevel also has direct influence on the damage values of a weapon and the amount of armor value on armor pieces. For leveling items it also interacts with the minimum character level required to equip/use an item (i.e. higher ilevel requires higher character level). Display of the item level in item’s tool tips can be enabled in the game’s options.
The quality (also called rarity: green/uncommon, blue/rare, purple/epic). The formula to calculate the item budget uses different modifiers, which increase the result with increasing quality. This effect, while not important at all for current end-game content (where everything is of the same quality; i.e. epic), becomes relevant while leveling up and at the release of a new expansion. You will often find green or blue items with a higher item level than epics from older content, which due to the modifiers in fact still have a lower item budget. For example a character decked out in Mount Hyal and Black Temple epics from Burning Crusade would hardly replace any of those items with greens or blues while leveling up in Northrend, before hitting level 80.
The slot modifier. An item has it’s budget modified based on what equipment slot it fits in. “Bigger” items have more stats on them, but in return they also cost more when purchased or need a larger amount of materials when crafted.
Slot modifiers:
1.0 (1/1): head, chest, legs, 2-handed weapon
0.75 (3/4): shoulders, hands, waist, feet
0.68 (17/25): trinkets (this value is debatable/unconfirmed since many trinkets have some form of proc ability, that is difficult to quantify)
0.65 (9/16): wrists, neck, back, finger, off-hand/shield
0.42 (27/64): 1-handed weapons
0.32 (81/256): ranged weapons (other than wands)
0.31 (5/16): wands
Upgrading gloves, trinkets or rings will yield a lower increase in item budget that upgrading a chest piece or headgear would give. To maximize your immediate gain it would be preferable to upgrade the bigger item first. However, if you pay for the upgrade with a limited resource (e.g. Emblems or high-end crafting materials) it can be more cost-effective to buy the smaller item first (and saving the surplus resources for the next purchase). Often a smaller item’s cost/budget ratio is better, which means in the medium term you would gain more by getting multiple items faster (especially if you can get a set bonus faster this way). On the long term it doesn’t matter, though, since most serious raiders will earn more emblems than they need anyway.
An example: Bob just did his first couple of Northrend heroics. He is still wearing an old helmet from Sunwell Plateau (ilevel 159, item budget 114) and some green quest item for the shoulders (ilevel 174, budget 75). Now he has enough Emblems of Triumph to buy a new piece for either slot. Both new pieces are ilevel 245 epics, which equals to a budget of 256 for the head and 192 for the shoulders. Minus the budget of the existing items this would be an upgrade of 142 budget points for the head and 117 for the shoulders. However, the head costs 75 emblems, that’s 1.89 budget points per emblem, while the shoulders cost only 45 emblems: 2.6 budget points per emblem – and there’s 30 emblems left over, which would allow to buy yet another upgrade pretty soon.
This also means for example that one 2-handed weapon gives a 16% higher item budget than dual-wielding two 1-handed weapons (which is the reason why 2-handers are so popular “stat-sticks” for hunters, by the way).
In case you really want to know, the exact formulas behind all this are:
For epic items: itembudget = e((ilevel + 344.36) / 106.29) * slotmodifier
For rare items: itembudget = e((ilevel + 287.14) / 97.632) * slotmodifier
For uncommon items: itembudget = e((ilevel + 292.23) / 101.18) * slotmodifier
(”e” is a mathematical constant and equals approximately 2.71828183.)
Sometimes, due to a glitch in the Matrix, an item finds it’s way into the game that is either under or over budget, meaning it has either less or more stats on it than it should have, according to it’s item budget. These items are usually considered buggy and will be fixed in a patch.
Now we know where exactly the total item budget comes from, but there’s one more factor that plays a role for the final result: Many stat have a stat modifier, meaning some stats are more “expensive” or “cheaper” than others.
Stat modifiers:
1 (1/1): primary stats (STR, AGI, INT, SPI) and combat ratings (crit, hit, exp, haste, ArP, dodge, parry, block)
0.67 (2/3) Stamina
0.5 (1/2) Attack Power
0.86 (6/7) Spell Power
2 (2/1) Mp5
0.07 (1/14) Bonus Armor
0.33 (13/40) Block Value
This concept becomes transparent if you look at gems of the same quality: It is safe to assume that all current epic gems (excluding JC-only gems, of course) have the same item budget. One gem for example can have 20 Strength, 30 Stamina or 40 Attack Power, all of which is the same value once the above modifiers are taken into account. Note that due to rounding, Spell Power gems are actually slightly under budget (by 0.33 points). This does of course not mean that a cheaper stat is automatically better than a more expensive one. Strength for example converts into 2 Attack Power per point for melee classes (except rogues), which directly balances out with the stat modifier.
In WoW-terminology, itemization describes the distribution of different stats on an item, i.e. how much of which stat an item has.
Sockets are an interesting topic on their own. It is not entirely clear how Blizzard handles sockets when creating an item, however the current assumption goes as followed: First, an item without any sockets is designed, and the stats allocated. Then the stat value for a random stat is reduced by 16 points for each socket on the item. This means generally that a socketed item is always superior to one without sockets – the more sockets the better. For one, with current epic gems the budget of the socket is lower than that of the gem, meaning with each socket you effectively get 4 points of item budget for free. More importantly though, you gain the possibility to trade a less desirable stat for a high priority one and you gain flexibility. On top of that, the socket bonus is just that: A free bonus with no cost.
Another interesting anomaly are melee weapons for spellcasters. Caster weapons have their dps value reduced, to create additional item budget, so to speak, which is invested into additional spell power.
As a side note (just for completion’s sake), stats do not simply have their modifiers applied and then are added up, to meet the item budget. There’s some more math involved here:
itembudget = (((stat1 * statmod)log(2)/log(1.5)) + ((stat2 * statmod)log(2)/log(1.5)) + … + ((statn * statmod)log(2)/log(1.5))) 1/(log(2)/log(1.5))
(log(2)/log(1.5) equals to approximately 1.7095)
Part 2: conclusion
So much for the cold theory of item mechanics. We now know why exactly one item is “better” than another one, but where do we go from here? Earlier I said “the more stats on an item, the better”, but that is of course only half of the truth. I also mentioned “high priority” stats and “less desirable” stats. Each class values stats differently. While some of these choices are obvious (a tank will want defensive stats and Stamina and a mage above all Spell Power, while Attack Power is not so much a good idea for a mage), some of them aren’t (Haste is a strong stat for an Assassination rogue, while Armor Penetration would be better for a Combat rogue). Stat weighting has a major impact on how good an item actually is for a specific class or spec, and it is far more difficult to quantify than what was described in part 1. The problem is that it is individual for each class and spec, and can even differ significantly depending on gear or play style.
An example: Agility is the highest priority stat for a Survival hunter: additional Agility will generally result in the highest dps increase, compared to the same amount of stat value of all other stats (with the exception of hit rating; more on that later). But it is not self-evidently clear just about how much better Agility is than any other stat – that depends highly on the character’s gear. Let’s assume a quite well geared hunter, for whom 1 point of Agility gives 2.0 dps, while 2 points of Attack Power (i.e. the same value after stat modifier) give 1.5 dps, 1 Crit Rating gives 1.2 dps and 1 ArP gives 1.8 dps (all of these are somewhat realistic values). If we now look at a couple of hypothetical items:
Axe of Agility: 100 Agi, 50 AP, 75 Crit
Fist of Fury: 75 Agi, 100 AP, 75 Crit
Sword of Power: 50 Agi, 150 AP, 75 ArP
All three items have the same item budget, however due to the itemization and stat weighting they would give significantly different increases in dps. At first glance one might think the Axe of Agility is obviously best, because it has by far the highest amount of the highest priority stat. But it actually would only be second best, with 327.5 dps, after the Sword of Power with 347.5 dps (the Fist of Fury loses with 315 dps). It is a common mistake to look only at the highest priority stat. But if we were to assume a different weighting (for a less well geared hunter Crit will be more valuable and ArP less) this might look quite different. This is why it is absolutely mandatory to research your class thoroughly. Generalized example stat weightings can often be found in class / spec guides. Better would be to actually calculate those values specifically for your character.
There are two more things I want to mention in this context; firstly stat caps. A cap marks a point from where on increasing a stat will either only yield a strongly reduced benefit (this is called a soft cap) or no benefit at all (hard cap). Not every stat has a cap and existing caps can differ significantly (again: research your class). Increasing Attack Power or Spell Power for example will always increase your damage by the same factor, no matter how much you already have: There is no cap for these stats. But when it comes to hit rating it is obvious that you cannot hit with more than 100% of your attacks and spells. While for many classes/specs hit rating below 100% hit chance is a high-priority stat, it becomes absolutely worthless at above 100%. Increasing a stat above the hard cap should be avoided as much as possible, since it is a complete waste of item budget.
A more complex example: Haste reduces casting time and global cooldown on spells down to a minimum of 1 second. Meaning, for an Arcane mage the hard cap is reached once the casting time of Arcane Blast is reduced to 1 second. This is not really achievable just by stacking haste rating from gear alone, but there are a number of buffs that have to be taken into consideration: Wrath of Air totem, T10 set bonus, Icy Veins, Heroism/Bloodlust, possibly Black Magic enchantment and use/proc effects from trinkets. This means there are quite a few different numbers for what the cap for haste from gear could be, depending on what buffs are available. Ultimately, with all possible buffs stacked up and regular haste from gear, the mage will easily be high above the cap, even though only for short amounts of time. But this can mostly be avoided by not stacking active buffs (e.g. not using Icy Veins during Heroism/Bloodlust). Therefore it would not be advisable to stop stacking haste on gear (which overall is a very effective stat for an arcane mage) as soon as the lowest possible soft cap is reached, but rather to search for the sweet spot, where loss of dps from over-capping (during periods of stacked buffs) starts to out-weight loss of dps from being below the cap (during periods without buffs), always keeping in mind what buffs you actually can expect to have.
Secondly, stats scaling: Most stats scale linearly, meaning, like mentioned above, increasing a stat by a certain amount will yield the same gain, independently from how much of that stat you already have (up until the cap, if applicable). 1 point of stamina will always give you 10 points of health, regardless of if you have 1000 stamina or 2000 stamina.
But while most combat ratings scale linearly, they also scale interdependently and depending on attack power (or spell power, respectively): The absolute result from increasing one stat depends on how much of another stat you have. For example, if you increase your AP, your normal attacks hit harder, and as a result your crits will also hit just as much harder. This means, while 45.91 crit rating will always translate into 1% of crit chance, that 1% might translate into a gain of maybe 200 dps or 300 dps, depending on how high your AP is.
In contrast to this, defensive stats (defense rating, dodge, parry, armor) have diminishing returns. The more you have, the lower the effect of additional points in these stats will be. The base conversion rate for dodge rating for example is 45.25 for 1% of dodge chance. A tank who already has a high amount of dodge however will find that he needs significantly more dodge rating for the same increase in dodge chance. This mechanic was added to the game to prevent tanks from becoming truly unhittable, i.e. able to fully avoid every single attack made against them.
Armor penetration on the other hand is kind of a black sheep. It counteracts armor, which has diminishing returns, which means armor penetration has increasing returns: It becomes more effective, the more you have (again, up until the cap).
Fortunately it is hardly ever necessary to actually use the formulas I quoted above, and do all the math yourself, because there is a number of tools that will do this for you. The range in complexity goes from relatively simple gear rating systems like the well-known GearScore or rating websites like Be Imba!, up to highly complex simulations, like Rawr. There also are a selection of specialized simulations for individual classes or specs. While all of these tools can be useful (you will need a simulation to find out the actual stat weighting that applies to your character, for example; it is hardly ever feasible to calculate this by yourself), always be aware of their limitations! In it’s basic form, GearScore for example will only show the budget of an item (i.e. what was described in part 1 of this guide), but it will not judge on how well it is itemized for whatever class/spec is using them. A warrior could equip spellcaster cloth-items from heroic Icecrown Citadel and earn an exceptionally high raw score, even though those items are actually useless for that class.
More complex models will not make this mistake, but even the most elaborate simulation will always remain just that: a simulation. While their creators go to incredible lengths to make them as accurate as possible, there’s only so much that can be done. Almost every encounter in the game has different mechanics that are quite impossible to simulate accurately: adds, target switching and movement, only to name the simpler things you run into. Also, the more complex a system is, the more prone it becomes to errors.
An example: According to Shandara’s famous hunter dps spreadsheet, any half-decently geared hunter will deal more damage in a Marksman (MM) spec, compared to a Survival (SV) spec. However, the total dps number the sheet gives under the bottom line is a bit deceiving. A closer look at the detailed numbers will show that with MM, the majority of the damage shifts towards Steady Shot and Auto Shot. Both of these shots can only be used while standing still, while Explosive Shot, the main damage dealer for SV, is an instant and hence can be used while moving. Therefore, on encounters that require high mobility, MM loses a lot more of it’s dps-potential than SV. The spreadsheet cannot model this, it simply doesn’t take any movement into consideration. In the end, with high enough gear, and played by a skilled person, MM will still outperform SV. But this is not as easy and obvious as the spreadsheet suggests.
Which is the prompt for my final remark: The best gear in the world won’t help you much if you don’t know what you’re doing. A tank who can’t hold aggro because he doesn’t use the right abilities to generate threat is a bad tank, no matter how excellent his gear is. And if he gets that right, he’ll still be responsible for wiping the raid, if he doesn’t move out of the Lich King’s Defile… In the end, to beat the most difficult encounters, you will need both the appropriate gear and skill.
Further reading:
Elitst Jerks Item Level Mechanics thread
WoWwiki Item Level article
Warcraft Hunters Union Armor Pen Rating and Armor Pen Cap (for Hunters, but also generally interesting)
Maintankadin Paladin tanking 101 (with details about diminishing returns)
Caveat lector:
With the release of the Cataclysm expansion, many of these mechanics will change dramatically, most likely rendering this guide completely obsolete.
