Finally got my drop and kinda figured out the blocking manipulation.
Steps:
1) Start from Pogahn passage.
2) Talk to Priest for Blessing on Kournan Kills if you're not a Sunspear Castellan.
3) Clear all the Kournan groups inside the fortress (by careful pulling BTW, making sure you dont pull the groups and the boss's mob at the same time). Sometimes a Camp Commander spawns with 1 of the groups that can lob heavy artillery on you and you AI buddies, don't stress just make sure the boss's mob be pulled last.
4) Once the inside of the fortress is clear, pull the boss's mob and make sure to call your targets so your AI buddies will focus on your target. Don't worry about the boss getting killed coz it takes a lot of hits to take down the Acolyte. Once all the boss's henchmen are dead, run away back to the res shrine. The boss if he follows you will stop following at the end of the bridge.
5) Now do the flag your hench method. Making sure their names are greyed out.
6) The Blocking manipulation starts. Sometimes there is a male NPC or female NPC with two others walking back and forth by the entrance to where the Acolyte hangs out. Depending on the spawn, the male NPC will be permanently stationary on the perfect blocking spot. If all 3 NPC's are moving, you have to time it correctly and click on the NPC (Male or female). Only 1 of those 3 will act as your blocker. If the blocker is not in the right position your blocking chances are close to nothing meaning you cant solo the boss
7) Once blocked, self explanatory, Kill the Acolyte of Grenth and hope for a green drop.
Note: Thanks to Meat Shield for posting his Photo Capture of the farm.