Relevant Talents used:

Void Tendrils
Body and Soul
From Darkness, Comes Light
Desperate Prayer
Divine Insight (Twist of Fate also works well)

iLvl: 480

Please ignore Recount as it was displaying information from a previous attempt.

Al'Akir is the final boss of Throne of the Four Winds raid. The boss himself has 3 phases. The most challenging phase in terms of both DPS and survival requirements is phase 2. Phase 2 is also the longest lasting phase throughout the fight

Phase 1 is very easy. Standing at melee range of the boss results in about 20-30k melee swings. This damage is perfectly healable but the trick in fact is to stand out of the melee range of the boss. This causes the boss to channel Electrocute on you which ticks for nature damage every second for 10 seconds. The initial ticks are negligible and even the final ticks are only up to 15k or thereabouts. This damage is easily healable with Renew and Devouring Plague. Standing at melee range also works but it would probably require more healing and thus the phase itself lasts longer. A wall of tornadoes will spin around the platform, and the only way to get past them is to find the gap within the wall. Another notable ability is Wind Burst, which knocks back the player. So in order to prevent getting knocked off the platform, make sure to run to melee range during the cast and wait for the knockback. Phase 2 begins when the boss reaches 80% health

During phase 2, the boss no longer casts Wind Burst but the Tornado wall remains in play. Additionally the boss will apply a debuff called Acid Rain that does 500 damage every second and this stacks every 15 seconds. Hence phase 2 is all about pushing the boss to phase 3 before the stacks reaches unhealable levels, typically 25 stacks is the maximum amount of stacks a priest can endure with all cooldowns. Unfortunately phase 2 is extremely long, and doesn't end until the boss reaches 25%. Luckily the boss has provided a method to increase our DPS against him for this phase. Every 20 seconds a Stormling add will spawn. Killing this add results in a stackable 10% damage taken debuff on the boss. Therefore another challenge of this phase is to kill the Stormlings in an orderly fashion so that the debuff on the boss continues to stack without dropping. The Stormlings themselves has a 10 yard aura which deals around 6k nature damage. Void Tendrils can be used to root them in place in order to avoid this aura. Like phase 1, it is recommended to remain out of melee range as the Electrocute damage taken is a lot less than melee swings. The later stages of this phase can be quite messy due to the high Acid Rain stacks combined with Electrocute so definitely save defensive cooldowns for later.

When the boss reaches phase 3, he will grant you the ability to fly at 300% speed. First thing to do is to finish off any remaining Stormlings. For phase 3, either fly to the very top or the very bottom, but remain close to the boss as Wind Burst is back in play. The boss himself only does a weak Chain Lightning in this phase and does not melee. However every 15 seconds or so storm clouds will gather at your altitude in which case you will need to either descend or ascend depending on whether you moved to the very top or very bottom. When knocked back by Wind Burst remember to move back into melee range of the boss to prevent being caught in the swirling vortex. Aside from that, phase 3 is extremely easy for soloing (despite being the hardest phase when it was current content), and if you reach phase 3 with at least 2 minutes on the enrage timer, it is pretty much a guaranteed win.