There's a lot of information here that is wrong or confusing.
Maestro cannot be slowed. You get the immune to attack speed changes message if you try.
At the start, three of the banshees will spawn in the open area before the organ but not will not move.
At 75%, two accompanists spawn on the piano. They appear to be rooted. I had trouble slowing them but they're not immune. I only tried magic slow.
If you back your group/raid into the back corner by the organ, you can avoid the banshees from ever aggroing you. I chose the corner to the right as you enter his room. Tank was in line with the bench and everyone was packed in the corner. It can be tricky to position Maestro without him getting on the organ so you may have to run back and forth a bit until you get it right.
If you fail to properly position yourself, the banshees will aggro. Since they can be avoided, they should be. The one that procs the mana drain is pretty devastating if you're not killing fast. The charm banshee was resisted every single time with 400-500 MR on my characters. The banshees each have about 50-60k hitpoints and can be slowed if you decide to take them on. Max hit was mid 600s.
Moaning banshee casts Thought Vortex (mana drain) A LOT, every 8-10 seconds. High priority first kill.
Screeching banshee casts Scorn's Beckon (charm). Easily resisted.
Wailing banshee didn't seem to cast spells.
Ultimately, my group damaged him for 600k, but a lot of that was from regenerating at 75% health when the accompanists come out.
Tank had 12.3k HP, level 65, 22 HSta, 18 HAgi, 950ish AC. Max hit was 1207, with 1324 hits in 742 seconds, and an average hit of 493. I took 354K total damage. I had 500 MR but his lifetap still hit for 687 on average.
I managed to do this in era (Hate 2.0 comes in LDoN) with one group consisting of Paladin, Cleric, Druid, Bard, Monk, and Shaman.
Edited, Jun 23rd 2020 12:54am by stealingjoy
Edited, Jun 23rd 2020 12:54am by stealingjoy
Edited, Jun 23rd 2020 12:55am by stealingjoy