- at 75% and 50% hp the boss will summon one of the previous bosses and become unvulnerable untill you kill the ghost boss. Those ghosts have about the same mechanics as they have when you fight them earlier in the dungeon
- the boss spawns a totem which drains everyones ressources. It should be destroyed asap
- the boss spawns waves of adds. Especially the stoneshapers hit hard, but I think they only spawn on hardmode
- the boss spits some orange stuff on the ground. If an add collects it before you do, it will get buffed
- from time to time a random player has to destroy a statue. Then all his skills will be replaced with some sort of inner fire and he can only target statues with it. The difficult thing is that only his team mates see which statue needs to be destroyed, so TS or some other form of voice chat is very helpful
- at low hp the boss starts doing some cross shaped aoes. From my experience it's easier to just heal through it than trying to avoid them, but thats a mechanic where I'm not happy with the way how we deal with it.

I think the reveal synergy just allows you to show the player which statue he has to destroy if you don't communicate with each other. But I rarely use it since I'm almost always on TS with my group.

https://www.youtube.com/watch?v=afSugrIwKP8

Destroying the totems quickly can't be stressed enough. This fight is a clear DPS check, and if you can't be on-point and burn 200Kish HP in 10s, you'll probably wipe. The totems continue to spawn in her last, area-wide-pinwheel aoe phase, too, so make sure you are staying alert for that. A totem in her final phase will still probably wipe the group if left unattended unless she's really close to death. Stacking and burning usually works best in her last phase, with aoe heals being spammed on a tight group. The totem always spawn NEAR someone, so it's easy to melt.

Also, any time she SAYS SOMETHING--doesn't matter what--she's going to do one of her two repeating moves: curse someone with the inner-fire bar thingie, OR, drop a totem. I used to think she said specific things for each, but after farming the crap outta Vet RoM, I've learned her ranting isn't sequenced. And finally, and as to that last point, she will do those two attacks, on cycle, perpetually (until dead). It's always curse>totem, curse>totem, etc. There's about 30s between each phase, so just enough time to settle a curse or clear a totem.

Oh, and last pointer: if you're taking, do so away from the group and with the boss turned, ALWAYS. She does a conal AOE that crosses the entire arena and can one-shot DPS. I face her to the wall and keep her pinned. I always refresh the taunt when she speaks, just in case I'm cursed. That gives me 15s to control her while getting to a statue, and still keeping her turned.

Communication is key in this fight, and it's not recommended to do it without voice chat, even if you're pro.

The hard part is the enrage phase (which starts at 25%), when she both curses one player and summons a totem. This is the part where most groups fail. You can't just simply burn her, you must destroy the totem and the cursed player must be put back in the game ASAP.