Mage mechanics
From xenowiki
Mage FAQ: Basic Mechanics
This is an attempt to answer some of the questions about Mage mechanics that frequently arise on the forum. It's going to be somewhat freeform, as I expect it to expand as people add additional questions in the thread, so for now, don't expect neat categorization of the questions. If enough questions are added that it makes sense to organize them, I'll do so for version 2.
All About Talents
How Do Crit Talents Stack?
How Exactly Does Ignite Work?
Should I take Improved Fireball/Frostbolt in my build?
Do +Damage% Talents Affect Base or Total Damage?
How Do +Damage% Talents Stack?
All About Stats
How Does +Damage Work?
How Do the Various Combat Ratings and Stats Convert to Useful Numbers?
How much Hit Rating do I need?
How Does Haste Rating Work?
Do Haste Rating or Haste Effects Reduce the Global Cooldown?
How Does Haste Rating Compare with Crit Rating, Hit Rating and Damage?
How Much Should I Emphasize Hit/Crit/Damage?
All About Talents
Do not expect to find build recommendations or the like here. This information is covered in the general Mage FAQ. What you can find here is explanations of some of the less-obvious mechanics behind the way some of the talents work.
How Do Crit Talents Stack?
Short Answer
Untalented spells: 150% crits
Spells with Spell Power only: 175% crits
Frost spells with Ice Shards only: 200% crits
Frost spells with Ice Shards and Spell Power: 225% crits
Fire spells with Ignite only: 210% crits
Fire spells with Ignite and Spell Power: 245% crits
Long Answer
This question generally comes in two forms: "Do Spell Power and Ice Shards stack?" and "Do Spell Power and Ignite stack?" The answer in both cases is simply "yes," but that leaves the question of exactly how much damage you get out of the stacking. Here's how it works:
Let's say you have a totally untalented Frostbolt that hits for 1000 damage. On a critical strike, the damage would be 1500 points. The extra 500 points is your "critical strike damage bonus." This is commonly referred to as a "150% crit," and is the standard critical strike for any spellcasting class.
So, first, let's look at Ice Shards. With 5 points, this talent increases your critical strike damage bonus by 100%. 100% of 500 is 500, so your total damage is 1000 + 500 + 500 = 2000. This is commonly referred to as a "200% crit."
Now Spell power. This talent increases your critical strike damage bonus by 50%. 50% of 500 is 250, so your total damage is 1000 + 500 + 250 = 1750. This is commonly referred to as a "175% crit."
If we combine them, their bonuses are simply added together: 1000 + 500 + 500 + 250 = 1250. This is commonly referred to as a "225% crit."
Now let's say it's a 1000 point Fireball (yes, it's feeble, but it's an easy number to work with). As with Frostbolt, the standard crit is 150%, with a 500 point critical strike damage bonus.
With Ignite, you get 40% of your critical strike's total damage added as a DOT, so the Ignite damage is (1000 + 500) * 0.4 = 600. The total damage is 1000 + 500 + 600 = 2100, or 210%.
With Spell Power, but no Ignite, it works exactly like Frostbolt: 50% of 500 is 250, so the total damage is 1000 + 500 + 250 = 1750, or a 175% crit.
If you combine Spell Power and Ignite, you first determine the damage of the critical strike itself, which we just did: 1750. Ignite is then calculated from this value: (1000 + 500 + 250) * 0.4 = 700. Total damage is 1000 + 500 + 250 + 700 = 2450, or a 245% crit.
How Exactly Does Ignite Work?
Short Answer
Ignites do not roll in the manner they used to back in the Fire Mage glory days in Naxxramas. Nor do new Ignites overwrite old ones. Except in very rare cases, you should now always get 40% of your crit damage in Ignite damage. No more, no less. It may sometimes be delayed, but it'll get there.
Long Answer
You can think of it this way: every time you crit, 40% of your crit damage is deposited into the "Ignite Bank." If two seconds pass without a crit, half of the damage is withdrawn from the Ignite Bank and applied to the target. If another two seconds pass, the other half is withdrawn and applied to the target, leaving the bank empty. Here is an example:
0 seconds: Fireball crit for 2000 (800 Ignite damage banked)
1.5 seconds: Scorch crit for 1000 (400 Ignite damage banked; 1200 total)
3.5 seconds: Ignite ticks for 600 (600 remaining)
4.5 seconds: Fireball ticks for 2000 (800 Ignite damage banked, 1400 total)
6.5 seconds: Ignite ticks for 700 (700 remaining)
7.0 seconds: Molten Armor crit for 125 (50 Ignite damage banked, 750 total)
9.0 seconds: Ignite ticks for 375 (375 remaining)
11.0 seconds: Ignite ticks for 375 (0 remaining)
Total crit damage: 2000 + 1000 + 2000 + 125 = 5125
Expected Ignite damage: 5125 * 0.4 = 2050
Actual Ignite damage: 600 + 700 + 375 + 375 = 2050
Should I take Improved Fireball/Frostbolt in my build?
Short Answer
Yes. The DPS increase provided by the reduced casting time always outweighs the decreased damage resulting from the lower Damage coefficient.
Long Answer
Here's the math (thanks to Aerinia):
A = average base spell damage
B = elemental spell coefficient
Damage per second without improved fireball = (A + B)/3.5 = (2/7)A + (2/7)B
Damage per second with improved fireball = (A + .9B)/3 = (1/3)A + (3/10)B
Since 1/3 and 3/10 are both greater than 2/7, you always achieve a net DPS gain from taking improved fireball over not taking improved fireball. Your DPM suffers, though, as you do get less damage from each fireball.
The same analysis can be applied to frostbolt with similar results.
The only time you would not take these talents is for a deep Arcane build that only casts Fireball or Frostbolt with Presence of Mind or as an opener.
Do +Damage% Talents Affect Base or Total Damage?
Short Answer
These talents affect your total damage. Don't let anyone tell you otherwise.
Long Answer
One of the sources of confusion with these talents is that, unlike many talents, they alter the tooltip damage of the affected spells. A Frost mage with Piercing Ice will show a higher damage range for Frostbolt than a Fire mage without Piercing Ice. This is one of the cases where the tooltip system falls down on the job; it doesn't show what your gear is doing to the damage range, it doesn't show what most of your talents are doing to the damage range, but for some reason it does show what these three talents are doing to it. And people assume that what they see in the tooltip is the only affect the talents have.
This is not the case. These talents have been tested many, many times, and they definitely increase the total damage, including gear and other damage bonuses.
How Do +Damage% Talents Stack?
Short Answer
All +Damage% talents are multiplicative.
Long Answer
Any combination of +Damage% talents multiplies your total damage. In other words, if you have Fire Power and Playing With Fire, your Fire spells receive (1.1 * 1.03 - 1.0 = 0.133) = +13.3% damage, not ((0.1 + 0.03 = 0.13) = +13% damage. Piercing Ice and Arctic Winds result in an 11.3% multiplier, etc.
All About Stats
This section includes discussion of the various combat ratings and other stats that come on our gear, how they work, and what they're good for. And what they're not good for.
How Does +Damage Work?
Short Answer
Any spell with an untalented casting time of 3.5 seconds will receive the described amount of extra damage. Any spell with a shorter casting time will receive less, any spell with a longer casting time will receive more.
Long Answer
+Damage gear is usually described in tooltips with the phrase "Increases damage and healing done by magical spells and effects by up to X." There are other similar wordings used in some tooltips, but the effect is the same, and the description is misleading, as some spells actually receive more than the listed amount.
Every spell has what is called a "damage coefficient." This coefficient is based on the spell's casting time, with 3.5 seconds being the divisor. The untalented casting time of the spell is the dividend. Instant-cast spells, such as Fire Blast, are treated as 1.5 second spells (the length of the global cooldown). Thus:
Fireball: 3.5 / 3.5 = 1.000
Arcane Missiles: 5.0 / 3.5 = 1.429
Scorch: 1.5 / 3.5 = 0.429
Fire Blast: 1.5 / 3.5 = 0.429
We multiply the +damage total of your gear and buffs by this coefficient to determine how much benefit that specific spell receives from the +damage. Let's say you have +900 damage (using normal rounding):
Fireball: 3.5 / 3.5 * 900 = 900
Arcane Missiles: 5.0 / 3.5 * 900 = 1286
Scorch: 1.5 / 3.5 * 900 = 386
Some spells, such as Frostbolt, have a coefficient penalty based on an additional effect (0.95 for its snare, in the case of Frostbolt):
Frostbolt: 3.0 / 3.5 * 0.95 = 0.814
The Empowered Frostbolt, Fireball, and Arcane Missiles talents provide bonuses that are additive to the base coefficient:
Fireball: 3.5 / 3.5 + 0.15 = 1.150
Frostbolt: 3.0 / 3.5 * 0.95 + 0.1 = 0.914
Arcane Missiles: 5.0 / 3.5 + 0.45 = 1.879
The Improved Frostbolt and Fireball talents reduce the coefficient multiplicatively with a 0.9 modifier:
Fireball: (3.5 / 3.5 + 0.15) * 0.9 = 1.035
Frostbolt: (3.0 / 3.5 * 0.95 + 0.1) * 0.9 = 0.823
Note that this is unique to these talents; most talents and effects that reduce casting time do not create such a penalty. Spell Haste, for instance, has no effect on your benefit from +Damage gear, nor does using Presence of Mind to cast a spell instantly. Arcane Blast receives the value expected from its 2.5 second base casting time:
Arcane Blast: 2.5 / 3.5 = 0.714
There are some unique cases, such as Pyroblast, which have seemingly arbitrary coefficients. Pyroblast gains a total 171.43% benefit from damage gear (as expected from its casting time), but only somewhere between 100% and 120% is applied to the direct damage, with the remainder applied to the DOT.
AOE spells suffer a penalty as well; they gain approximately 1/3 the benefit that would be expected from their casting time. The exact coefficients were adjusted slightly for each spell in 2.0.
How Do the Various Combat Ratings and Stats Convert to Useful Numbers?
Short Answer
All conversions apply only at level 70.
12.6 Spell Hit Rating = +1% chance to hit
15.7 Spell Haste Rating = 1% haste
22.1 Spell Crit Rating = +1% chance to crit
39.4 Resilience Rating = -1% chance to receive a crit, -2% damage taken from crits
1 Stamina = 10 health
1 Intellect = 15 mana and 0.013% chance to crit (0.276 Crit Rating)
1 Spirit = 0.125 mana/sec when not casting
1 Spirit = 0.019 mana/sec when casting with 3/3 Arcane Meditation
1 Spirit = 0.038 mana/sec when casting with Mage Armor
1 Spirit = 0.056 mana/sec when casting with Mage Armor and 3/3 Arcane Meditation
1 Spirit = 2.000 mana/sec when Evocating
How much Hit Rating do I need?
Short Answer
Assuming you're fighting same- or +1-level mobs and players in PvP, and +3 level raid bosses, you need the following Hit Ratings to max your hit chance at 99%.
Fire/Frost mage, no Elemental Precision: 51 soloing or PvP, 202 vs. raid bosses
Fire/Frost mage, Elemental Precision: 13 soloing or PvP, 164 vs. raid bosses
Arcane mage, no Arcane Focus: 51 soloing or PvP, 202 vs. raid bosses
Arcane mage, 3/5 Arcane Focus: 0 soloing or PvP, 126 vs. raid bosses
Arcane mage, 5/5 Arcane Focus: 0 soloing or PvP, 76 vs. raid bosses
Long Answer
Your maximum hit rate is 99%. Your base hit rate depends on level of the target you're attacking compared to your own:
Same level: 96% vs. mobs and players
+1 level: 95% vs. mobs and players
+2 level: 94% vs. mobs and players
+3 level: 83% vs. mobs, 87% vs. players
Bosses are generally treated as +3 level targets, so you need to increase your hit chance by 16% to max it out at 99%. It takes 12.6 points of Hit Rating to increase your chance to hit by 1%. So subract any +Hit% you have from talents from 16, and multiply the rest by 12.6 to find your target Hit Rating.
How Does Haste Rating Work?
Short Answer
1% Haste Rating increases the number of spells you can cast in a given amount of time by 1%, assuming the resulting cast time is not less than 1.5 seconds.
Long Answer
Many people assume that if you have 10% haste, this means your spells cast in 90% of the usual time. To use Frostbolt as an example, this would result in a cast time of 2.5 * 0.9 = 2.25 seconds. This is not correct.
In fact, to find the new cast time, you use this formula:
talented cast time / (1 + haste%) = hasted cast time
So in the example above, we get 2.5 / (1 + 0.1) = 2.2727 seconds
In 60 seconds, without that haste we could cast 60 / 2.5 = 24 Frostbolts. With the haste, we can cast 60 / 2.2727 = 26.4 frostbolts, a 10% increase in DPS.
Do Haste Rating or Haste Effects Reduce the Global Cooldown?
Short Answer
No. The global cooldown is immutable.
Yes in 2.4
Long Answer
Testing to confirm this answer has been performed by many people both here on the WoW forums and on the Elitist Jerks forums. It has been tested several different ways, all with the same results, and may be considered conclusive. You can read about Zaldinar's testing here
In 2.4 it will lower to a max of a 1 second GCD.
How Does Haste Rating Compare with Crit Rating, Hit Rating and Damage?
Short Answer
If you end fights with excess mana, and your spell rotation primarily uses spells with a 2-second or higher casting time, Haste Rating is a good stat; if both those things are not true, it isn't.
Long Answer
Haste Rating is unique in that every 1% Haste increases your DPS by a reliable 1%. Point for point, this is superior to every stat but Hit Rating; once your Hit Rating is maxed out, Haste Rating is the best stat for pure DPS increase.
However, Haste Rating doesn't improve your efficiency at all. You produce the same damage per mana spent, you just produce it faster. So if you find yourself short on mana, you're better off taking Damage and Crit Rating to increase both your DPS and DPM.
Also, Haste Rating cannot increase casting speed beyond the 1.5 second global cooldown (see above). So if your casting rotation includes many spells that cannot be improved with Haste -- Scorch and fully-stacked Arcane Blast are the main culprits -- then Haste will be less useful to you.
You can use http://tc.awenet.com/ to calculate how valuable Haste Rating is to several common specs.
How Much Should I Emphasize Hit/Crit/Damage?
Short Answer
No matter what your spec, unless your current gear is already dramatically unbalanced, Hit Rating > Damage > Crit Rating.
Long Answer
Here's a dramatically simplified explanation: first, it takes fewer points of Hit Rating (12.6) to get +1% hit than it takes points of Crit Rating (22.1) to get +1% crit. So even if 1% hit and 1% crit were equivalent (which they're not), a single point of Hit Rating is worth a larger fraction of that 1%.
Second, it's been tested and proven that spells use a two-roll system: one roll determines whether you hit the target or not, and if you hit, a second roll determines whether it's a crit or a regular hit. What this means is that the value of both Damage and Crit Rating is reduced by your miss rate.
Now, here's where it gets tricky: as I said, no matter your spec, and assuming your gear is reasonable, Hit Rating > Damage > Crit Rating. However, the actual relative values -- how much better is Hit Rating than a point of Damage -- depends on your spec and your current gear.
For a very, very rough rule of thumb, you could use the following values:
Deep Arcane spec: 1.0 Hit Rating ~= 1.5 Damage ~= 2.9 Crit Rating
Deep Fire spec: 1.0 Hit Rating ~= 1.4 Damage ~= 2.2 Crit Rating
Deep Frost spec: 1.0 Hit Rating ~= 1.4 Damage ~= 2.5 Crit Rating
33/28 Arc/Fire spec: 1.0 Hit Rating ~= 1.5 Damage ~= 2.0 Crit Rating
Arcane/Frost spec: 1.0 Hit Rating ~= 1.7 Damage ~= 2.0 Crit Rating
For a more exact determination for your own gear and spec, you can use Muphrid's formula:
+1 hit rating = .0793/h*(m/r+d) +damage = 1.75/h*(1/b+c) +crit rating
h = hit chance
m = average base damage
d = +damage
b = crit bonus
c = crit chance
Additional resources for this question
Irontygress's Mage Calculator: http://forums.worldofwarcraft.com/thread.html?topicId=106863613
The Theorycraft-o-Matic:
http://forums.worldofwarcraft.com/thread.html?topicId=1271907242
