The immense storm wyrm Altairus maintains an unyielding vigil over the hovering platforms of the Vortex Pinnacle. The very energies of the storms pulse through this being, and he is said to command the wind currents that buffet the elemental fortress.
Abilities
Call the Wind — Altairus periodically calls to the wind, creating a constant wind in one of four cardinal directions. Depending on the direction of the wind, the player's location, and Altairus' location, the player receives either the Upwind of Altairus effect or the Downwind of Altairus effect.
Upwind of Altairus — If the prevailing wind blows over the player before reaching Altairus, then the player has their attack and casting speeds increased by 100% and movement speed increased by 30%.
Downwind of Altairus — If the prevailing wind blows over Altairus before reaching the player, then the player has their attack and casting speeds decreased by 100% and movement speed decreased by 30%.
Chilling Breath — Altairus chooses a random player, then turns and casts a Chilling Breath in their direction. The breath inflicts 25500 to 34500 Frost damage to all enemy targets in a frontal 120 degree cone from Altairus.
Lightning Blast — Any player not standing on Altairus' platform is blasted with an immense blast of lightning, inflicting 55500 to 64500 Nature damage.
Twisting Winds — Altairus' platform fills with fast moving twisters. Any player that touches a twister is dealt 11700 to 12300 Nature damage and knocked straight up.
Strategy
It's possible for all players to get the Upwind buff.
Altairus only casts Lightning Blast at players that attempt to leave the platform.
Wind flows on the platform of Altairus: all dps and healer should stay upwind of the boss in
order to gain the Upwind of Altairus buff and avoid the negative Downwind debuff.
Tank will need to stand Downwind from the boss in order for melee dps to receive the buff. If there are no melee, however, it is possible for tank to stay Upwind too.
Altairus will randomly change the direction of the wind; everyone needs to adjust their positions accordingly to stay upwind of the boss.
Rogues are extremely powerful against Altairus, energy regeneration increases with attack speed, with [Slice and Dice] and other buffs, the Rogue has a practically unlimited energy pool and can easily double their DPS. [Safe Fall] also prevents the fall damage from the tornadoes.
Heroic
Fast moving tornadoes called Twisting Winds are all over the platform. You must avoid them: if you get caught up in one you will take about 12,000 Nature damage and get knocked up and away, possibly off the platform. When you land you will take fall damage.
He will not only frost breath the primary target, he will turn and target a random group member and breath on them, hitting anyone in that direction.
Everyone stand in the hitbox and move as needed to get the buff.
The tank needs to focus first on avoiding the tornadoes, second on keeping frost breath from hitting the party. If necessary, you can tank him at the edge of the platform, as shuffling the party around the boss in the center makes it very likely that someone will get caught in the tornadoes or breath.
DPS and the healer need to focus first on avoiding the tornadoes, second on staying out of his face, and last on aligning themselves with the wind. The tank cannot always put Altairus in a position that makes it easy to get the upwind buff. Do not chase the wind if it requires you to get in the boss's face or run through a lot of tornadoes. The wind will shift soon anyway, and this is more of a survival test than a DPS race.
Altair means the flying one or bird of prey in Arabic. As many gamers can likely recall, this is also the first name of the main charater in Assassin's Creed.
Altairus is pointing north, which fits with him dropping the Reins of the Drake of the North Wind.
Altairus
Call the Wind 
— Altairus periodically calls to the wind, creating a constant wind in one of four cardinal directions. Depending on the direction of the wind, the player's location, and Altairus' location, the player receives either the Upwind of Altairus effect or the Downwind of Altairus effect.
Upwind of Altairus — If the prevailing wind blows over the player before reaching Altairus, then the player has their attack and casting speeds increased by 100% and movement speed increased by 30%.
Downwind of Altairus — If the prevailing wind blows over Altairus before reaching the player, then the player has their attack and casting speeds decreased by 100% and movement speed decreased by 30%.
Chilling Breath — Altairus chooses a random player, then turns and casts a Chilling Breath in their direction. The breath inflicts 25500 to 34500 Frost damage to all enemy targets in a frontal 120 degree cone from Altairus.
Lightning Blast 
— Any player not standing on Altairus' platform is blasted with an immense blast of lightning, inflicting 55500 to 64500 Nature damage.
Twisting Winds 
— Altairus' platform fills with fast moving twisters. Any player that touches a twister is dealt 11700 to 12300 Nature damage and knocked straight up.
[Slice and Dice] and other buffs, the Rogue has a practically unlimited energy pool and can easily double their DPS. 
[Safe Fall] also prevents the fall damage from the tornadoes.
[Amulet of Tender Breath]
[Mantle of Bestilled Winds]
[Hail-Strung Belt]
[Axe of the Eclipse]
[Skyshard Ring]
[Reins of the Drake of the North Wind]
Patch 4.1.0 (2011-04-26): Altairus now spawns closer to the center of his platform, away from the edge.