Found this on gamefaqs and thought I would share. enjoy.
Now that Ahune is out today, I have some quick advice for everyone attempting the fight.
It's a very fun and chaotic fight, with adds out of the ying yang and good times.
He's located in Slave Pens, both normal and heroics modes, and drops epics in both versions, though the items do differ. As far as I can tell, the only difference in loot is he drops cloaks on normal, and amulets (and a BoJ) in heroic. The rest should be the same.
WoWhead link:
Lord Ahune - NPC - World of Warcraft
Summoning
He's actually very quick to summon, in the second chamber of Slave pens. There's a giant crystal just on the left of the entrance past the hall. BUT, he's summoned towards the back of the room. So be sure to clear the majority of the room before starting the event.
I'm not sure if summoning him is a daily quest like the headless horseman, so don't be surprised if it is. Also, there are no pre-quests necessary to fight him.
The Fight
Now the fun begins. It's a chaotic fight, with needs for lots of AoE. If you didn't bring any AoE, good luck.
Also, any frost resistance (totem or aura will do) is a nice boon to have.
Throughout the whole fight, there will be some swirling frost animations on the ground. These eventually turn into spikes which deal about 500 damage, launching you into the air for fall damage of about 10-15% of your max health. Needless to say, avoid them!
... Most of the time, it's kinda fun to be launched.
Phase One - INSANE ADD CONTROL REQUIRED
He'll spawn three different types of adds, an elite and a zerg's worth of non-elites.
He is completely unattackable in this phase, just stands there and looks cool.
Elite - Ice (Rock) Elemental
Have this guy tanked, as he hits fairly hard. Only one will be spawned during first phase. He also has a stacking debuff that deals frost damage (similiar to Lord Barov in scholo, except it stacks), so melee DPS will probably need some healing. He's not the real challenge of the fight though
Non-elite - Water Elemental
These guys hit for not much damage... but he'll spawn a TON of them. You'll see up to 30 of them, easily up to 6-8 at once. They have only 2000 or so health, so AoE like no tomorrow! I found that having a lock spamming SoC on the elite makes for some easy control and damage. Try to keep them bunched up to make AoEing them easy. A prot paladin tanking helps, but not that much because they're being constant spawned, so gaining aggro isn't so easy.
Non-elite - Air Elemental
These guys are just annoying. Low health like the water elementals, similiar damage... yet only a few will spawn. These will do a pull move, dragging you towards them and interrupting any casting. Just AoE them like the water elementals. These won't spawn until Ahune enters Phase Two at least once.
Phase Two - DPS Frenzy!
This is an extremely easy phase, even easier than the headless horseman.
Wipe up the adds if any are left (ideally, two at most), and just start DPS on his frozen core.
Ahune does NOTHING during this phase except shrink a little. Take off as much health as possible (30-50%) and it goes back to Phase One, you have 25-30 seconds.
It's a crazy and chaotic fight, a bit tougher than Headless Horseman (but not much), but VERY fun.
At the kill, loot everything there is from a chest that spawns right in front of where he stood.
Take you loots, and don't forget to grab the Shards of Ahune (group loot) so you can get a nice tabard.