I had about 20-30 attempts before 5.4 as retribution and I could never kill him, as I couldn't beat enrage timer and I kept wiping at around 20%. So I decided to wait for 5.4 and once I get 4p T16 I'll be able to doit. This is actually my 2nd kill as I killed him last reset while doing usual ICC mount run. Once I reached him I gave it a go and oneshooted it, same with this kill. I don't have 4p T16 as matter of fact I don't have any SoO gear. My IL is 544 and I killed it with help of Legendary cloak which gave me extra ~20 mil dmg.
What I lacked was AoE dmg to zerg adds down plus get cleave on LK pre 5.4.
Here's some info about kill:
As mentioned above my IL is 544 and I have legendary cloak, so I recommend being around 540+ and having legendary cloak to attempt LK as ret.
I used Seal of Insight to have constant healing so I can keep myself at 90%+.
300 strg food
With 5.4 you should get BL and ofc stat drums
Glyph of Divine Storm
Glyph of Double Jeopardy
Glyph of Divine Protection
You can also use Exo glyph for cleave.
Tier 1: Speed of Light - You can use any out of three.
Tier 2: Fist of Justice - Very helpfully against Horrors to stun them at low hp.
Teir 3: Sacred Shield
Tier 4: Unbreakable Spirit - Very helpfull talent combined with Glyph of DP
Tier 5: Divine Purpose - I used RNG for extra cleave plus combined with DS glyph extra healing.
Tier 6: Execution Sentence - For max dps/dmg
In PH 1 make sure you nuke Horrors as prio. They do way to much dmg when they manage to hit you. For little Gohuls just cleave them down and make sure you're at 90%+ all the time before Infest cast.
Transition PH, prio Spirits and nuke them down as fast as posb. You can set macro for Judgment to focus down Orbs or you can get near them as they spawn and just cleave it down. Make sure you cast FoL or WoG on yourself you need to keep yourself up.
In PH 2 avoid Defile and make sure you're at 90%+ before Infest cast.
PH 3 is zerg phase you don't need to keep your HP above 90%+ as LK doesn't cast Infest at that point.Use Divine protection for each vile spirit attc and burn boss down.
This is my first time making vid so acept my appologies if video above is bad or music to loud.
I always liked soloing things as ret, I kinda hated that I had to do LK as prot but day finaly came to doit as ret.
I hope you enjoy the video and if you have any question feel free to ask.