4.0 Fire Mage Guide (PvE)

Since I couldn't find a nice 4.0 pve fire mage guide anywhere on the internets I thought I would have to do my own. Because of the recent changes done to stats in general and mages in particular I can't guarantee this to be perfectly correct. Also this has not been tested in Cataclysm yet. What I have read about fire mages in Cataclysm, most of this still holds however. Any input is greatly appreciated!

Table of Content
- Introduction
- Talents
- Glyphs
- Stats
- Gems
- Rotation

Introduction
What role does the fire mage have in 4.0/Cata? What can you expect from playing a fire mage?
More than any of the other mage-specs, fire mage is about dot-damage. In fact it is so important that our mastery affects nothing else. Alot of fire mage talents focus around spreading this fire damage and getting increased stats when more than 2 targets are affected by our debuffs. What does this mean for our playstyle?

Issues
In the current content, very few boss-fights include more than 1 target at the majority of the fight. Taking ICC as an example, some bosses have adds which could be used to maximize dps. But in the same way this means as soon as there are no adds our dps drops significantly. One could argue that aoe always will outdps single-target dps, of course. Problem with fire mage is that doing aoe-damage is part of our core-mechanics and standard rotations. Some of our most important talents depend on us being able to do aoe-damage. I don't know how the fights will be in Cata, but I can say that the way fire mages work now isn't optimized for our current content. If you want to top mage-dps, I'd go with another spec as it is now. Fire mages are too dependant on the perfect setup to be at their max potential.

Potentials
Even though things might look glum for fire mages at a first glance, one could also argue that there is enormous potential for fun and awesome amounts of damage as long as Blizzard know how to design the fights (i.e so we at least get an opportunity to use all our skills and talents at maximum efficiency). As soon as the fight mechanics go our way fire mages are extremely entertaining.

Scorch-build?
Some changes to some skills have also made people (EJ Forums) wonder if we're not better off using scorch as our main damage component instead of fireball.
Why a Scorch-build is a good idea;

• Talents like Improved Scorch that removes mana cost from Scorch would probably mean we'll never oom, allowing us to take other talents instead. 
• Talents like Improved Hot Streak are benefitted from more casts rather than slow, hard hitting casts. 
• With the right amount of crit the extra procs from Hot Streak would outperform the potential dpsloss from using Scorch instead of Fireball. Impact is also benefitted from more casts rather than slow, hardhitting ones. It would also significantly reduce our need for haste. 
• With the right talents Scorch is usable while running, making our dps way less affected by movement (of course we can, and should, use Scorch while running in a Fireball-spec as well). 
• It is easier to time reapplication of Living Bomb with a short-cast spell than long-cast spell. 
• Spell interruption is less of an issue.

Why a Scorch-build is a bad idea;

• Fireball does have higher dps than Scorch. With low crit (less than 35-40%), the builds seem to do about the same damage. With ridiculously low crit (less than 30%, you shouldn't even be fire mage then) a regular fire ball spec would probably be better. 
• There is a glyph of Fireball that increases crit-chance with Fireball by 5%, but no such equivalent for Scorch.

I've tried the different specs, using the same gear (and Fireball Glyph) and the Fireball build does deal more damage on a boss-dummy (with my gear about 2k dps more). I think in a raid-setting the easier handling of Scorch spamming could win out on Fireball Spamming however, not to mention you won't oom. With a regular Fireball rotation, and without any mana-efficiency talents like Clearcasting or Master of Elements, I oom after about 2 minutes on a dummy. With a Scorch build I'd probably have to go on for 10 minutes or more (never tried though). This means we have to place dps-talents into mana efficiency-talents, or try to regain mana mid-fight through Evocation. Either way we loose dps trying to regain mana if the fight is longer than 2-3 minutes using a Fireball spec. If this dps loss is greater than the dps gain from using a Fireball spec is hard to say, the specs are undoubtedly close in damage output and might need personal testing. It may also vary from fight to fight. Your stats and gear could determine whether you win out on a Scorch or Fireball build/rotation. Maybe alternating between these rotations is the best solution?

Frostfire Bolt- build?
Frostfire Bolt is alot like Fireball. It deals about the same damage and has the same cast time. With glyph of Frostfire Bolt it might however actually deal more damage than Fireball, in which case it would be better to use this than Fireball. Some preliminary testing seems to indicate that Frostfire Bolt isn't worth using in our rotation however (not to mention to replace Fireball/Scorch entirely). It seems to deal considerably less damage.

Talents
Because of the above-mentioned issues, there are also some issues to how we would want to place our talents. Since some talents actually require us to have multiple targets they are essentially useless at any time that we don't have multiple targets. This also means the loss of alot of synergy between talents.

Main Tree
Tier 1
Master of Elements: Mana is an issue for mages as much as it ever has been. Since we really don't want to use Spirit (read more about stats further down) our main income for mana will be talents like this. If you're interested in a Scorch-build, this talent is basically useless however.
Burning Soul: Because Fire Mage is alot about throwing Fireballs, any cast time lost is dps lost. This all depends on how big an issue you taking damage is. Some boss aoe-mechanics also have spell knock-back mechanics for instance, so even if you don't get actively hit my something you might be passively.
Improved Fire Blast: Fire Blast will be more important to us now than before. Increased crit is also an essential component of our damaging mechanics.
Tier 2
Ignite: CORE TALENT. You are useless as a fire mage without this.
Flame Power: 3% extra damage straight off is nice. We don't get the Fire Orb skill until level 81 though.
Blazing Speed: Since movement seems to become more important in Cata than it has been before, this could potentially become a good pve-talent. For now it is more of a pvp-talent.
Impact: This talent is in synergy with the talent Pyromaniac (see further down). It's usefulness in our current raid-content is limited however, we can only hope this changes with Cata. It does also reset the timer on Living Bomb, which is bad.
Tier 3
Cauterize: Since dying always is the ultimate dps-loss, this could also become useful in a pve-setting. There are several reasons why you could die in a raid - 1. You stood in fire. 2. The raid wiped. 3. Lack of healing. Cauterize will only be truly helpful in the third case (as for the first case, l2p instead ;))
Blast Wave: An aoe skill. Synergizes with Improved Flamestrike and Pyromaniac but will still only be useful when there are several targets. No longer has the knockback effect.
Hot Streak: CORE TALENT. There is no point in playing fire mage without this.
Improved Scorch: Only useful if you're interested in a Scorch-build.
Tier 4
Molten Shields: This could be an interesting utility talent for extra movement. Unfortunately the Blazing Speed effect doesn't kick in until after 30 seconds or after your Mage Ward dissipates due to absorbtion, which might make it a little difficult to time properly.
Combustion: Not everyone likes the changes made to Combustion. I do however. I think it's a great way to give us a nice tool that has to be properly used for us to maximize dps instead of just something to pop at any time for some extra damage.
Improved Hot Streak: CORE TALENT: You won't do any damage without this.
Firestarter: Even if you're not interested in my Scorch-build this is a very good talent. It allows you to be not so useless for when you have to move alot, like Halion phase 2 for example.
Tier 5
Improved Flamestrike: Aoe-talent. Synergizes with Pyromaniac, but is only useful when there are multiple targets.
Dragonbreath: Because of its limited range it is rarely useful in raid-pve. Since it is a prerequisite for Living Bomb we have to take it anyway.
Molten Fury: Talents like these aren't testable against dummies, but that doesn't make them less useful.
Tier 6
Pyromaniac: Very situational. In fact so situational it'll rarely be up in a raid-setting, maybe this will change in Cata. With a Scorch-build this is a less important talent. With a Fireball-build this will increase your damage output alot once it's up.
Critical Mass: 15% extra damage to one of our most important skills is awesome. 5% extra crit to our targets is also good, but generally applied by someone else in a raid.
Tier 7
Living Bomb: CORE TALENT. Don't even think about not taking this.

Off Trees
Arcane Concentration: With a fireball-build this is a really good talent. With a Scorch-build it is completely necessary.
Netherwind Presence: With a fireball-build this is a really good talent. With a Scorch-build it is less necessary.
Piercing Ice: We want tons of crit and thus we want this talent.

Fireball-build

Scorch-build 

Glyphs
I won't talk about them all, but the interesting ones (which aren't very many unfortunately):

Prime

• Living Bomb
• Pyroblast
• [Free to choose] But I'd go with either Mage Armor or Cone of Cold.

Major

• Fireball OR Frostfire Bolt - depending on which one you're interested in using as your main-spell. If you're using a Scorch-build this one is unecessary.
• Molten Armor
• [Free to choose] But I'd go with either Evocation, Invisibility or Mirror Image.

Minor
None of the minors change your damage in any way so you are free to choose any you like. I'd go with Slow Fall, Armors and Conjuring.

Stats
As you might have noted by now, there are four very important stats for a fire mage - Crit, Haste, Hit and Spellpower/Int (haste is less important in a Scorch-build however). Which one is more important?

Hit: Most important. If we don't hit with our spells, there is no meaning in even casting them. Since we no longer have any talents that give hit, we now need 17% through gear.
Crit: Without any crit our damage falls like a house built of cards. Crit is the very foundation of fire mage dps. Not all the spellpower or haste in the world could make up for a nice amount of crit.
Haste: One could argue that the more haste = more casts = more damage. Strictly speaking this is true of course, but that is setting aside all the side effects of our casts. Since a big portion of our damage comes from us critting one has to aim at as many as those hits being crits as possible. Even if we throw many spells, we'd do less damage if they never critted than if we used less spells and they all critted. Alot of crits = instant Pyroblast. Instant is alot of haste :P Hope you follow my meaning here.
Intellect: We want our spells to do a lot of damage when they hit of course. Nowadays we get spellpower through intellect. Intellect also gives us crit! 1 intellect only gives us one third of the crit that 1 crit rating does however, and this has to be taken into consideration.

1. Get the hit-cap (17%)
   
2. Get crit over 40% (at least! But the more the better)
   
3. Get haste over 20% (only if you've got a fireball/frostfire bolt build, if you use a scorch build you can focus on more Crit instead of Haste).

Reforging
Any stat on a gear piece that isn't one of the above should be reforged into mastery since reforging currently is our only source to mastery points.

Gems
Following the above rules for stats these are the best gems for us.

Blue - 20 hit Rigid Majestic Zircon, until capped. When capped it is mostly better to ignore socket bonus and go for Int, Haste or Crit (mostly Crit).
Red - 20 Int Brilliant Cardinal Ruby
Yellow - 20 Crit Rating Smooth King's Amber or 20 haste rating, Quick King's Amber (unless your haste is really low, it is probably better to gem crit though.)

In case you're curious the gems give the following stats;
20 hit rating = 0,76% hit
20 int = 20 spellpower and 0,12% crit
20 crit rating = 0,4% crit
20 haste rating = 0,6% haste (how much this reduces your cast time depends on the original cast time of your spell).

Rotation
What makes Fire Mages so much fun is the lack of a dull rotation or spamming of one skill. There will be plenty of Fireball/Frostfire Bolt/Scorch casting (whichever you happent to prefer), that much is true, but to do optimal dps as a fire mage you have to follow a set of rules and keep track of your buffs and debuffs.

1. Keep Living Bomb up. DO NOT CUT IT! Reapplying Living Bomb before it runs out is basically useless. Rather miss a second than reapply too early. It is no use applying it to a target that will die before the debuff runs out.
2. When Hot Streak is up, use it.
3. When Ignite, Living Bomb and Pyroblast debuff are on your target, use Combustion. (There are addons to help you keep track of this. I just use DoTimers).
4. Spam Fireball/Frostfire Bolt/Scorch

Skills with certain rules;
Mirror Image: The best time to use Mirror Image depends a little on the fight. Unless Blizzard have changed something I'm not aware of, it is still best to try to use Mirror Image just before Bloodlust. Unless the fight is long enough to use Mirror Image several times in which case it is best to use them from start.
Impact: Is not worth using if there is less than 3 targets. If you have between 1-3 targets try applying Living Bombs to all of them instead. It seems like Impact no longer resets the duration of Living Bomb on the target, in which case it is safe to use Impact procs as long as there is more than one target within 12 yards. It is still best to try to keep Living Bomb on all targets if they are between 1-3.