5th January 2013, Patch 5.1.0 ● Burning Legion EU - Aventurka
Affliction + Voidlord ● 484 iLvL
Talents: Harvest Life, Mortal Coil, Dark Bargain, Burning Rush, Grimoire of Supremacy, Kil'jaeden's Cunning
Glyphs: Demon Training, Siphon Life, Soul Shards

Difficulty: ★★★ Medium

The fight is a little bugged while soloing. This was my first attempt, so I made a few mistakes.
The fight against mini-bosses is simple, which is why I don't put them in this video. Do not stand at the front and the back of Halion.
P1 (Physical realm): Every time Fiery Combustion deals damage, it generates a Mark of Combustion charge on you. When Combustion fades or is dispelled, it unleashes a patch of fire proportional in size to the number of charges present at the time. You can use Unbound Will talent to quickly dispel first Fiery Combustion. Then you should reach phase 2, before the second Fiery Combustion will generate too much charges of Mark of Combustion. Get out of the Combustion as soon as possible, because it applies a stacking debuff. Remember to avoid Meteor and not stand in the fire. If you survive this phase, you succeed in killing Halion.
P2 (Twilight realm): At 75%, Halion shifts to the Twilight realm and opens a permanent portal so you can follow for Phase 2. In this realm, he does not use Soul Consumption (equivalent of Fiery Combustion), so stay here until the end of the fight. The only thing you need to watch out is Twilight Cutter. You should go through the beams only when you have an active Twilight Ward.
P3 (both realms): At 50%, Halion is present in both realms at the same time. This phase is almost the same as phase 2. Boss will heal himself and receive a buff called Corporeality. Depending on the value of Corporality, Halion deals and takes more damage in one realm than the other. Corporality will grow with time, so you only need to dps him and survive to the end of the fight. Good Luck and Have Fun!

More solo kills: http://www.youtube.com/user/AventuraStudio

My UI: http://i.minus.com/ibyOfUKi4407x2.png
Music: Realm of Power - Two Steps From Hell