!BOOM! Headshot.

Hunters and PvP. Blech. Anyone who's played a mage in a battleground knows that, as a general rule, hunters are to be avoided.

To put it quite plainly, hunters are designed for squishies. Sometimes they save our tissue paper wearing behinds, other times they giggle and shoot pointy sticks into those same behinds.
Anybody who's fought more than a dozen hunters in PvP knows that there are some general rules to fighting a hunter.

1 - Take the pet out of commission. (Fear, Frost Nova, Hamstring...)
2 - Take away the hunter's mobility. (Frost Nova, Hamstring, that druid root thingy...)
3 - Unload as much damage as possible on the hunter, as fast as possible.

To quote a certain large angry feline, hunters provide "Massive quantities of sustained, ranged DPS".
The key word here is "ranged" and "sustained". Countering both of these is the only way to win against a hunter that has any experience in this game.
As a mage, your guiding principles are simple. Polymorph the pet if possible, root the hunter, and the whole time, unload any and every instant spell you have to get that hunter down as fast as possible. As a general rule, taking the pet out removes anywhere from 30% to 50% of the hunters damage, depending on their spec, and marksman hunters are the only ones with any real amount of burst damage.
So, as mages, our strategies are as follows:

• Polymorph the pet, if time allows. This is risky to do, BM's will simply break it and trash your squishy behind. As well, you waste at least 1.5 seconds of the encounter to this, which is time you could be damaging the hunter. Another downside, the hunter gets a free 1.5 seconds to do whatever they want. Shoot you, drop a trap, whatever.
• Blink is a very effective spell to use againts hunters. It has two uses: 1 - getting into dead zone territory faster, 2 - breaking LoS when hunter pops SquishyKiller...err, Beast Within.
• While first running at a hunter, use every instant you have. Fireblast, Cone of Cold, Presence of Mind, Dragon's Breath, Blastwave, hell, even an Arcane Explosion won't hurt.
  
• If you're fire, use Dragon's Breath to get off a fireball, or at least a scorch or two. You will desperately need that damage. If you're Frost, pop Frost Nova as soon as you can, and try very, very hard to get off a Shatter combo. Chances are very good you'll be met with "Scattershot" or "LOL MY PET IS BIGGER THAN THRALL'S CHAIR". If the former, trinket out of it if possible, and at least get an Ice Lance nuke out of it.
• Beast Within is very dangerous, if you let the hunter use it to it's full potential. This is your strategy for countering it : RUN. You have to survive the next 19 seconds on your own. Break LoS, blink away, /beg, have a paladin bubble you, whatever it takes. Having Ice Block immensely alleviates the difficulty. You only need to survive 9 seconds. Again, break LoS, whatever. And congratulate yourself if you survive, you just wasted a BM's most powerful weapon. Feel free to /giggle.
• DEADZONE! This is your best weapon against a hunter. They cannot melee you or ranged attack you, and is currently the only way to deal anything remotely approaching serious damage to a hunter. If you can manage to get a hunter rooted with none of the "IWIN" buttons, you can get a full cast off here.
  
• Silencing Shot. /shudder. If you get hit with this, two things you can do. Ice Block out of it, or break LoS so the hunter can't take advantage of it. Drop behind a pillar, run into a building, whatever.
  

At this point in the game, unload your instants again. If the hunter's not dead by now, chances are pretty good you're going to lose. BM's are easier than the others, they have nothing now. Frost Nova again, Shatter combo, you win. Marksman may have Scattershot up again; if you have a cooldown monitor addon, it is invaluable against hunters. If you don't have one, get one. If he doesn't have it, Shatter with impunity. If you're not frost, props to even living this long.

Please note that having a Water Elemental is incredibly useful for fighting a hunter. Basically, free extra damage, and an extra root. Heck, you can even get another Shatter combo off of it, if you're deadzoning.

If you can make it into a second deadzone cast and pull it off, you've basically won at this point. Some hunters are tougher and require another Instant Cast smackdown, but they drop easy once their cooldowns are gone.

If you find yourself unable to break LoS when you need to, unable to somehow get the pet out of the picture, or find yourself trapped/wingclipped to a standstill, be prepared to eat some very painful pointy things. Blink can be a help here, if you have the cooldown, you must make every effort to stop that hunter from gaining range on you.
If the hunter does get range and keeps his mobility, you've lost control of the situation. And when you lose control of the situation, you lose the fight. Plain and simple.

This also why Blizzard's announcement of dispatching the dead zone worries me so much. A class flaw it may be, but this class flaw was the only thing we mages had to get an actual cast off against a hunter. Without the deadzone, we will be stuck with Instant Casts. With only instants, we simply will not have enough damage to drop the hunter before they drop us

IN CONCLUSION

How to beat a hunter
1 - Remove the pet from the equation
2 - Take away the hunters mobility
3 - Drop them as fast as possible with Instants
4 - Abuse the deadzone so hard, the hunter trainers /cry



APPENDIX

Ever wonder how a hunter does so much damage to us? It's simple. Almost all of their attacks are based on physical damage. This is mitigated by armor... and guess what? You got it. We mages have no armor. This is why we eat auto-shot crits of over 1k damage each, from undergeared beast master hunters who didn't put points in marksman.


EDIT: Fixed a few typos