First Curio - Reverse Engineered Goblin Death Bomb. (This saved my Bacon when I could not reach a Potion or my mitigation was on CD.)
Second Curio: LOOT RAID-R (I had DPS enough to pop his shield consistently, but not if I needed to down an Add that somehow did not drop from the initial wave of bombs, or bombs were out of reach).
BM Hunter Setup:
ST loadout via WoWHead, No alterations
Growl off
Play Dead on Bar
Usual buffs. I did not prepot in my successful run.
Tactics:
Start on the right side, as you enter, next to the first flashing blank neon billboard/sign. Every single attempt that went beyond 40% began with this starting position.
(1a: I think there are no slots for the adds right as you enter. That was throwing me off. I may be wrong about that, but this position is the best. Possible secondary position on the left side, same relative position).
Have Pet Play Dead at the start. Gather threat, then after the boss leaps, reactive pet.
Keep Mend Pet on CD. Successful attempt did not see pet die for even one moment.
Do not put yourself next to the wall itself, thats where the boss goes. You are outside, having the boss against the wall.
MOST IMPORTANT PART
WAIT until ALL adds are spawned, and aim for the MIDDLE one. This is where I was messing up the most. I was willy nilly firing em off. sometimes to the right, sometimes to the left. MOST of the time, by aiming at the very middle one, I was able to three shot the entire line.
Kite him around the arena, from your starting position, counter clockwise. I was doing far too small kiting. You want to make sure that the boss is plenty far awhile from occupied slots. I think there is a cool down on those slots.
I managed used the Damage potion at around 20%. I probably panic used it, too early. Not sure about that.
General Tips
Read all the forums and reddit posts you can. I have learned loads from all the threads I have seen.
Record Yourself and watch them. I kid you not, This was the defining factor I think in my getting this. I was able to really see where I was going wrong, what was killing me, what abilities I had, etc.
All in all, if I can do it…well I am not going to say anyone can, because this was the most hectic, chaotic, RNG based, “I have to everything right” “by the skin of my teeth” fight I have ever done. But dont think you cant because you get discouraged. Keep at it.
I channeled my inner Darth Bane to be honest. For a moment. Then I calmed, and channeled Qui-gon. There is only the living force. Live in the moment, let the moment flow, and you will find your way.
I must admit, my “total rage” mode is fierce burning hatred inside, outside just a scowl of intense concentration. I don’t want anyone to get the wrong idea of me throwing tantrums or anything (externally. internally, I was flipping tables, lol)
I had my thread with replays of my failure. And I kept on failing. I had an idea how to beat Underpin ?? but I kept failing on the same mistakes. I cant be consistent as the fights becomes more chaotic, the longer I stayed on the fight.
Today, I stopped making attempts. Instead, I went to get the 40k Mementos Void Dragon Mount from Horrific Vision.
Also, I watched Superman and Jurassic World Rebirth.
Not sure, but I am no longer trusting myself that I would beat the Underpin??. But I will still keep on trying.
I had probably 150+ attempts before I killed it, maybe more. I wasn’t tracking. It was a LOT! And the overwhelming majority of those wipes were with Underpin at 70% hp or more. When I finally killed him, I had never had a wipe with him below 35% and on my kill I even messed up the shield and he healed once.
All I can say is that my best attempts were when I was patient and didn’t try to get greedy (like kicking a bomb before moving out of a 1-shot mechanic). Also the initial OP’s advice on big moves between add waves is essential to keeping them grouped up.