Key talents here are:
- Frost Warding
- Improved Frost Nova
- Improved Blizzard
- Improved Cone of Cold
- Ice Barrier
- Water Elemental
A link to the complete build is here
Basic Strategy for AoE grinding:
Find your mobs. Try to avoid ranged mobs and / or casters, they have a nasty habit of hitting you with ranged attacks and casting spells. This is not condusive to successful AoE grinding.
Plan your attack. Running in screaming LEEEEEE ROOOOY and spamming Arcane Explosion isn't going to cut it, you need to be aware of your surroundings if you are going to have a hassle free AoE experience. First rule - always have ice barrier up.
Naturally the first thing you do then, is cast ice barrier. Mount up immediately, and gather 4 - 6 mobs by riding over the top of them. (wait until you get the hang of things before you go rounding up a dozen, although that will be totally doable with a little practice) Drag them to the killing field. This should be a relatively clear and safe area nearby where you don't risk pulling adds or pats halfway through your AoE.
Iceblock and wait. All the mobs will surround you and group together in a nice tight bunch, which is exactly what you want them to do.
Release your iceblock and cast Frost Nova, then run two paces away from the group. At this point you need to do a quick check that none of the mobs have resisted your nova. If one has, use your macro for casting cold snap and frost nova to get another nova off instantly, trapping the loose mob and keeping the group together.
As you begin to pull larger and larger groups, you will find one mob resisting your nova more often, so it is vital to have this macro ready, as a single loose mob can be the difference between a successful AoE pull and death.
Now that all your mobs are safely grouped and nova'd, it is time to blink.
Don't blink into another group of mobs!
Run another step or two. This will put you at approximately maximum Blizzard range from your group of mobs (first 2 paces + blink + another pace) and cast blizzard on your pack of mobs. You want your blizzard to cover ALL of the mobs, but be as close to your toon as possible, ensuring the mobs have to spend as much time as possible running through your blizzard to get to you.
At this point, if you have the talent Frostbite, things will fall apart. Some but not all of the mobs will get snared by frostbite proccing off the blizzard. The group will spread out, preventing you from AoE damaging all of them at the same time. This is why an AoE grind spec cannot include this talent, no matter how cool it is.
Once your first blizzard has been going for about a second or two, all the mobs will have the improved blizzard debuff. Congratulations, that was the hard part. Next you cast another blizzard as soon as the first finishes, but this one so it is right in front of you.
By now the closest mob in the pack will be about to walk into your next blizzard, which will keep the debuff up and keep them walking at a snail's pace. They will get to you eventually, however, but since you have Improved Frost Nova your cooldown will be up, and you can snare the mob pack again.
After two full blizzards and two frost novas, the mobs are likely to be almost dead. Most of the time a crit-happy cone of cold on the freshly nova'd mobs at your feet will be enough to finish them off.
If not, don't worry, you just slowed them again with the CoC, so blink away and repeat.
Advanced AoE grinding tips and tricks.
Ok, so you can round up and destroy about 10 melee mobs of equal level to yourself and not die. Time to expand your repertoire young padawan!
How to bring them down faster:
There are a few ways you can kill your mobs a bit faster, and most of the time you should avoid using these methods as they generally result in some kind of negative trade-off for the quicker kill, in terms of excessive mana usage, excessive damage taken, or wasting a lot of cooldowns.
Sometimes, you have to employ thse techniques or you will flat out die. Best to know them, even if you don't have to use them. Of course, when you want to pull 25 mobs... You are going to need every trick in the book, so listen up.
Method 1: Hit me, I can take it.
Cast ice barrier, round up your mobs on FOOT using AE to damage as many of them as much as possible while you are gathering the mobs. Refresh ice barrier whenever possible (it is a good idea to cast it, then wait 20 seconds, then pull, so you can re-cast it as soon as it gets destroyed by incoming damage)
Do not use iceblock, once you arrive at the killing field, throw up a couple more AE's until the mobs are packed, then nova, blink, blizzard, blizzard CoC, AE, AE, AE, AE.
This method will kill the mobs faster, and unless something goes wrong you will probably only get one blizzard off. It will also hurt. Potentially a lot. I don't really do this unless I have to, as you also risk running out of mana at the worst possible time.
Method 2: It's not what you know, it's who you know.
As a frost mage, your Water Elemental is you bestest friend, and during AoE grinding things are no different. This method is great for the ridiculously incredibly big pulls. Got 25 mobs? You are gonna need help with that.
Here's how you play it. Start things off like a standard pull. Ice Barrier and mount up, then pull EVERY SINGLE MOB IN SIGHT (trying to avoid ranged and casters as mentioned earlier)
Iceblock to gather the mobs in the killing field. This is the part where you realise how many mobs you actually just pulled. It's OK, you have an entire iceblock duration to get used to the idea that you are surrounded by a very large number of (hopefully) melee mobs who are all going to hit you just as soon as you let them.
Nova, take a step, re-nova if you need to.
Blink! Now cast your Water Elemental, followed by a blizzard.
The beauty of this method is that you are now looking at a huge pack of mobs about 30 yards away from you, all are under the effect of improved blizzard and coming your way. When you use your Elemental to cast a Freeze on the pack, you can root them in place just as your initial frost nova is wearing off. This will keep them in place for another blizzard, and you will have plenty of time to re-nova them if you have to when they eventually get in range.
Another benefit of this method is when a mob gets loose and hits you, your water elemental will be all over it like a fat kid on a cupcake, leaving you to blizzard the rest of the pack in peace.
Method 3: YOU WILL DIE IMMEDIATELY. ALL OF YOU!
Commonly used on easy pulls where risk to the mage is minor, and there isn't really any need for any of that fancy kiting business. Gather with AE (Always have Ice Barrier up. Always!) Nova, flamestrike, CoC, Arcane Explosion until they are finished. Nothing too special about this method but it will get rid of a lot of pesky mobs in a hurry if they are upsetting you in any way.
Zupa's favourite AoE grinding spot @ lv 70
At level 70 a good location is between Kirin'var village and Manaforge Coruu in Netherstorm. Here you will find a bunch of sunfury researchers just waiting to be rounded up and killed en masse. A word of warning, however, they have casters patrolling around. These will need to be removed prior to your AoE killing.
Thankfully, being ranged, you can pull them with a flying mount by flying low over their heads, without disturbing their melee counterparts.
Drag your casters off to your killing field, kill them, then go gather the melee mobs. The respawn timers at this site are just about right for a single mage to grind here constantly. Once you start getting more and more accomplished at AoE grinding, you may find yourself waiting for respawns.
When this happens to me I just pop over to the Kirin'var villiage and farm some primal mana. All the mobs there drop motes and the drop rate is great. Mobs are only arcane resistant and go down easy.
Unfortunately this location simply cannot support two farmers, so if you see another farmer, particularly if it is a mage, either kill them, ask them nicely to find another spot, or come back later, depending what mood you are in.
edit: your cold snap + frost nova macro should look like this:
#showtooltip cold snap
/cast cold snap
/cast frost nova