Right, I know Frost is not a spec that gets played a lot in a PVE setting, but I'm reposting Kuni's guide from MMO-Champion (Original Link) for those of us (such as myself) who like to play something a little different to the mass of fire mages out there.
Frost PVE: 4.3.3
Preface
Raiding as frost. Many people will laugh at such a proposition. I will admit, there aren't many good reasons to do such, either. Played to the fullest extent, in the best gear, there is a 7k DPS gain by switching to either arcane or fire; frost is far behind, but not completely worthless. Perhaps you need replenishment in your group. Maybe you don't raid at the highest level and prefer to play what you want to play. Maybe you have everything on farm and want a change of pace. There are a few fights where a well timed deep freeze will trivialize mechanics. Sometimes you just need someone who can kite.
Whatever the reason, you're here now, presumably to learn and improve. Playing frost well is somewhat of an art. It is fast-paced. It can crit over 100k with ease, if big numbers are your thing. It is a fairly twitchy spec, and heavily influenced by lag or low framerates.
Read on.
Basics and Playstyle
Frostfire orb
Freeze
Deep freeze
Frostfire bolt with brain freeze proc
Ice lance with two charges of fingers of frost
Frostbolt
This is your basic priority system. The opening sequence is slightly different, and I will get to it after this section.
Frostfire orb will flood you with both fingers of frost and brain freeze procs. The damage from the orb itself is pretty decent since it works its magic while you continue your casting, but if you consider the damage produced by the procs, you're looking at a lot more potential damage out of one cast. This takes priority over deep freeze for this reason alone.
Freeze is a water elemental's spell. It should be bound to a spare mouse button if possible. It is a ground target AOE spell. It must register a hit on a mob to proc the two fingers of frost charges. Hitting nothing will give you nothing. The highest DPS you can produce with this is to use it as soon as it comes off cooldown, after clearing any charges you have saved with ice lance. Many will prefer to save it for deep freeze, to make sure nothing goes wrong and they always have deep freeze available. Both are valid styles, although the first is marginally better DPS.
Deep freeze is your spell that hits like a train. It requires a charge of fingers of frost to be used. If you do not have a charge ready as it is coming off cooldown, you must use your water elemental's freeze spell to generate two of them.
Frostfire bolt should be used as soon as brain freeze comes up, regardless of if you have a fingers of frost charge available. It does not stack, so if you lose a charge, you've suddenly lost that potential damage.
Ice lance should be used when you have two fingers of frost charges, when the buff is about to expire, or when you need to dump your charges due to the water elemental's freeze coming off cooldown.
Frostbolt is your filler spell.
You should be DPSing using molten armour. Evocation, used at 40% mana, and mana gem, used at 12500 mana under maximum, are more than enough to keep your mana around for any reasonable fight. Don't be afraid to conjure a new mana gem mid-fight should you use all three charges. Madness of Deathwing is the only example of a fight this long currently.
The opening sequence of a frost mage involves the use of cold snap. This spell resets all cooldowns that you use to DPS, providing absurd front loaded burst.
Frostfire orb > freeze > deep freeze > icy veins > cold snap > deep freeze
Use your second orb as soon as the first one has faded, or is about to fade. Having both up at the same time tends to waste a lot of procs, and thus a lot of potential damage. Use icy veins as soon as your first one expires as well, unless time warp was popped. In which case, cast it after it is over.
Tier 13 set bonuses provide us with a cooldown reduction on icy veins. Your opener is not changed, except that you will pop icy veins a second time, and any time after the first, when you have 8 or more stacks of stolen time.
Talents and Glyphs
The generic, multi-purpose spec for frost is 2/8/31. There are a few floating points, which you can allocate as you see fit. I figure most are self explanatory, but just in case, I will go through each one and the reasons behind each.
Mandatory talents:
Early frost: Faster casts is more DPS. The global cooldown with this active is 0.8 seconds, so don't worry about haste capping.
Piercing Ice: 3% crit. Need I say more?
Shatter: The bread and butter of why frost actually works. This triples your crit, including buffs and debuffs, when the target is considered frozen by a spell. It also allows the spell to benefit from your mastery.
Ice Floes: Cooldown reductions on two DPS cooldowns and a few other spells that do come in handy.
Permafrost: 1 point should be considered required, as that will allow your water elemental to heal off any incidental damage it suffers.
Icy Veins: Main DPS cooldown, usable multiple times in most fights.
Fingers of Frost: Allows the spells listed to benefit from shatter and your mastery. Bosses can't be frozen, so this is the only way you will ever be able to use them.
Improved Freeze: Water elemental's freeze generates fingers of frost charges, more charges is more DPS.
Enduring Winter: The only frost-specific raid buff. Maxing it out is recommended, as the 10% mana reduction is very useful since you should be running molten armour.
Cold Snap: See opening rotation section. Double cooldowns is incredible.
Brain Freeze: Adds another spell to fingers of frost, and hits fairly hard with mastery factored in.
Ice Barrier: Filler to get to deep freeze.
Frostfire Orb: 2 points required. The first point changes flame orb to benefit from frost's +25% frost damage passive, and the second point allows it to proc both fingers of frost and brain freeze, once a second for 15 seconds every minute.
Deep freeze: I like 6 digit crits. So do you. Don't tell me you don't.
Master of Elements: Same reasoning as enduring winter, this is just more mana for you to use.
Burning Soul: Incidental AOE damage will delay your casts, lowering your DPS. This prevents most of it, and if you have the 35% pushback protection raid buff from a paladin or shaman, you can't be pushed back by damage.
Ignite: This essentially reads 40% more damage to frostfire bolt. It seems an odd choice to take for such an uncommonly used spell, but it really does shine. When you start getting frostfire bolts over 50k, another 20k for free is just amazing.
Netherwind Presence: 2% haste is the highest DPS increse of the talents remaining.
Optional talents
Piercing Chill: This gives you some form of cleave by the way of extra proc chances on fingers of frost and brain freeze. It's not much, but it's a good talent if you'll be fighting adds.
Ice Shards: If you need a chill on blizzard, this is your thing. The extra range on ice lance is near worthless in PVE since your other spells don't reach that far, and most targets aren't running away.
Enduring Winter: You may opt to take 2 points out of this, just so you have replenishment and the extra points to grab something else you might need for your job.
Reactive Barrier: This will automatically fire ice barrier whenever you drop below 50% and it's off cooldown. This can be a lifesaver, or a wasted talent depending on the fight.
Prime glyphs have no wiggle room. These three are the highest DPS no matter how you cut it. Deep freeze, frostbolt, frostfire. Major and minor are personal choice, but I have put what is likely the best uses in the talent build linked above.
Stats
Intellect > hit > crit to shatter cap > haste to GCD cap > mastery > more haste > more crit
Hit cap is 17%, or 1742 rating. If you miss a deep freeze, you will end up kicking yourself. Try not to go above, as anything above is literally wasted gear. A couple points under or over is usual, though. 16.99% is still good, as you'll likely lose too much of any other stat to gain the 1 hit you need. In practical use, you won't miss while that close.
Crit cap is 33.34% raid buffed. This includes the 5% crit buff from ferals, fury warriors, elemental shaman, and some hunter pets; and the 5% crit debuff from fire mages and warlocks. This is due to shatter multiplying your effective crit rate by 3. All your spells under fingers of frost will crit at 33.34%. Intellect affects crit! The more int you have, the less crit you need to cap. Zumzumzum has created a calculator for shatter caps. http://toprealm.fr/Shatter.html This is a very useful tool, and I suggest you give it a look when you're reforging or planning gear.
There used to be a 2% crit suppression on raid bosses, but as of Cata, there is no evidence showing this to still be in effect. If you wish to be safe just in case, reforge to 34% raid buffed.
GCD haste cap is only really obtainable with icy veins up. Seeing as the 4pT13 drops icy veins to 24 seconds at 10 stacks, this is something you should consider. The cap is 1642, before you include your 2p. At this point, with 10 stacks of 2p and the 5% haste raid buff, you will hit 50% haste under icy veins, and your GCD is capped. Your instant spells no longer benefit from haste past this point.
If you don't have 4pT13, ignore this point. You will not practically hit GCD cap outside of heroism and icy veins without it, and haste retains value due to the long cooldowns.
After those three caps are met, your only option is mastery. This has no cap, as it's simply a linear increase in shatter damage. It is not a bad stat, it is simply out-stripped by the other stats, then becomes better than them after the above points.
Dragonwrath Interaction
Dragonwrath doesn't really play well with frost. It is mostly an issue with our procs and frozen states. Should it duplicate ice lance with 1 fingers charge, it will not gain the frozen state, and will most likely hit for ~5k. It will cast a second damaging ice lance, but if used on the last fingers charge, the copy will not gain frozen state, leading to most likely a non-crit, and no mastery bonus, since it was not a frozen target. Frostfire bolt is the same way. Since the copy wasn't a brain freeze state, it will not gain from fingers of frost, even if you had two. On the other hand, if you have two fingers of frost charges, and an ice lance on the first one duplicates, it will consume both charges, and both will be considered frozen state. It is this reason that dragonwrath doesn't benefit frost as much as most casters.
Deep freeze appears to be a special case. From my testing, it appears to always have the mastery bonus, and will not consume a second charge of fingers, but it doesn't appear to gain the shatter crit bonus. This is most likely due to the fact that deep freeze damage will never happen outside of a mastery influenced situation, thus it is most likely hard coded into the damage portion of the spell to always benefit without checking, or frostburn is coded to be a straight +damage effect on deep freeze instead of +frozen damage.
Miscellaneous
Gems
The current meta gem to use is burning shadowspirit diamond. This is +54 int and +3% damage when you crit, which requires 3 red gems. There is no argument and no contest for any other meta gem against this. You gem all red +40 int gems unless the socket bonus can make up for it. For example, the tier chest is red/blue with 20 int bonus. You would gem 40 int/20 int and 20 hit, to gain 20 int from the bonus. Net gain of 20 hit. Obviously use epic gems should you have access to them. T13 itemization works in your favour, as almost all slots are red with int bonuses.
Water Elemental Sound
Should you get sick of the water elemental bubbling sound, as I have, simply go into your WoW's Data folder, create a folder called Sound. Inside that, create a folder called Creature, then another inside that called WaterElemental. Now create a blank .wav in that folder and call it WaterElementalLoop.ogg, capitalization is important on these folders and the file. Make sure you change the .wav to .ogg.
Power Auras
Invisusira has a beautiful set for all specs of mage over at http://www.mmo-champion.com/threads/...1#post12303364
I have taken her general and frost sets and modified them to my own needs. I will post the import set codes here, since that thread is no longer a sticky and could one day be lost. These lack an aura for icy veins and stolen time.
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I take NO credit for this guide, it's a straight copy-paste from Kuni at MMO-Champion - Original link is at the top.
