Blindside — Standing behind Wrathion increases your damage dealt to him by 250%. Aura on Wrathion for the duration of the encounter.
Crumbling Arc — Wrathion jumps in front of you and does a semicircle AoE attack. It is an uninterruptable 3 second cast that you can dodge by moving out of the dust clouds. It hits for approximately 200k damage. Be advised that this ability is currently buggy, and you may get hit even if you are outside the dust clouds.
Reign of Fire — Fireballs rain down from the ceiling, doing damage if they hit you. You can easily dodge this by avoiding the black shadows the fireballs cast when they appear.
Blood of the Deathborn — 2 second cast creates a void zone that deals about 50k damage/second. This spell can be interrupted.
Neltharion's Tears— About every minute or so, Wrathion summons or resurrects 5 adds. They have 500k health and melee for approximately 35k damage.
Inferno— About 2 minutes in, Wrathion will spawn many images of himself, all channeling Inferno. A single attack (including AoE) will kill any images it hits. Hitting the real Wrathion will stop the spell and despawn all the images. If Inferno goes off, it will deal damage depending on how many images remain. This repeats 3 times in sequence.