From the visual clues, I would never expect it to actually be a pretty nasty tankbuster as well, even if I carefully avoid standing in the telegraphed dodge attack for start to finish.
Next time, try and make better animations/visual clues to such things.
Honestly, from tanking pov, it feels like it was bugged at some point during the beta/alpha and they decided to make it a feature rather than actually fixing it (actually for a lot of time I assumed its bugged).
I doubt that, since we don’t get the debuff one gets from actually stepping in the beam. But yes, it confused me for a while before I read the dungeon journal.
That’s not what the OP is saying. The problem is how it has a tankbuster baked into the initial cast, that isn’t very obvious.
Speaking of Obsidian Beam, it’s also incredibly frustrating how fast it is casted following Collapsing Night when half the time the boss straight up refuses to move towards the tank. She isn’t casting anything either, but will sometimes just stand completely still after casting Collapsing Night, making it very difficult to create some space to move around the beams.