Is limit break not a thing?

[Sigma-Astra]

Though as far as SB goes, outside of it being virtually required for the OS3 add phase, it's only applicable for the OS7 Bibliotaph or during the Shinryu Extreme burn phase to nuke both of his wings.

Tank LB3 was needed for Byakko EX if you wanted to just breeze through the run almost flawlessly during that second add phase. I have seen and been in parties where they've forgone it in order to just nuke the add themselves, but the DPS were spot on with no hiccups. You won't always find that in party finder.

However, I've also seen tank LB2 used where people STILL survived with maybe a minimal death or two on the second add phase as well. But, healers have to be on duty and fairly good as well for the damage mitigation and capping everyone off the moment you're not stunned anymore and avoid Fire & Lightning.