The quest chain for getting to Karazhan is no different for a hunter than it is for any other character. However, there is one thing a hunter should know.
Toward the end of the chain, you are required to beat Opening the Dark Portal in The Black Morass. The event in this instance is one long gauntlet. Gauntlet events spawn monsters at a steady rate. That means that the group's damage output must be able to keep up with the spawning of the new monsters, or the group will eventually wipe. In fact, inexperienced players consider this instance very difficult, exactly because they have never encountered a test of the damage-dealers before.
In other words, for possibly the first time in your career as a hunter, your individual performance is really important. You must perform well. In this way, this instance is much like most of the raid encounters that follow. Think of it as your first real test before you go raid. It is a great chance to practice your raiding techniques.
Before you go to this instance, set up your spec, add-ons, gear, pet, macros, and consumables just as if you were going to raid. Set up everything to maximize your damage output. See the other sections of this guide to see how to do that.
You will be required to attack either the big dragons or the small dragons. Most of the raid boss encounters will have you attacking a single target, so volunteer to be on the bosses, not the small dragons. Also, hunters have a difficult time with the melee dragons.
With good damage output, each portal will spawn only two or three waves of small dragons. With poor damage output, each portal will spawn six or more. Obviously, that makes things much more difficult.
Stay on the big dragons, but do not be afraid to help whoever is attacking the small dragons with the occasional Multishot, Intimidation, or Growl. Also, drop Snake Traps, Frost Traps, or Freezing Traps in the path of the small dragons as they march toward the portal.
Keep your mana up. After each portal, turn on Aspect of the Viper, mount up, ride to the next portal, and drink until you need to fight. Use mana potions in emergencies.
On , the second boss, use Arcane Shot to dispel his Hasten self-buff. Keep Scorpid Sting up to make his Mortal Wound debuff miss the tank more often. Have whoever is attacking the small dragons switch to the boss for the duration of this fight, then clean up the small dragons afterward.
Make sure that you have a damage meter set up, and watch it carefully during this encounter. As a Beast Mastery hunter, fully buffed, you should be able to output 300 - 450 DPS during these encounters with the gear that is available before Karazhan and heroic instances. You will absolutely need the high end of that for and , and more like 600 DPS when you get to . This instance is a good time to get started on that.
Temporus drops the and . Aeonus drops the . These are all nice pieces of hunter loot. The Hourglass, in particular, is a really nice piece of gear for doing damage. So, this run is worth doing multiple times, both for the loot and for the practice at raid-style damage-dealing.