This is a video of me killing Nalak in patch 5.4 while being phased over to the Magtheridon Server so that I can be alone with the boss. (I'm on Illidan so its almost impossible to kill a world boss alone)
From My Video Description on YouTube:
I take down Nalak with my 5 destruction warlocks. I have ~540 item level on all 5 along with 5 legendary cloaks.
I used glyph of eternal resolve, siphon life and demon training. My talents were Soul Leech, Mortal Coil, Soul Link, Unbound Will, Supremacy, and KJC.
My buffs were warlock self buffs, Blessing of the Animus (15% damage), Overgrown Lilypad (Symbiosis: Rejuvenation) and Crystal of Insanity (+500 stats)
Fight lasted 9 minutes and 53 seconds.
The hardest part was to get a kill of this boss without anyone helping. I'm on Illidan...So after killing him a few times with 2-10 people "helping," once they saw that I could sustain it. Finally, I asked another multiboxer to phase me over to a lower population realm. Thanks Pozy.
Nalak isn't a difficult boss, but with only 5 targets/party members you get hit with all the mechanics 100% of the time. My warlocks were each at 21-23 K Healing/Absorbs per second
I could only get around 50% of my characters DPS output due to using voidwalkers and spending most of my attention on embers and healing along with pet management and positioning. Nalak is able to kill a voidwalker in 2-3 hits if the rejuvenation and shadow bulwark were not up. Nalaks model is so large(long) that it was difficult to keep the voidwalkers close enough to be healed. I found that using interact with target and the forward key was the best way to keep my warlocks close enough to heal the voidwalkers and each other. The arc nova wasn't that big of a deal provided I was around 55% hp, so it wouldn't kill me.