When do you use petrified blood?

For BV occultist... i kinda see that the dmg buff is huge when you are low life , but i guess its just makes you a glass cannon without the use of progenesis and bloodnotch?

Great synergy with pathfinder's op life flasks for big tankiness. If not, it allows for Pain Attunement use, you get permanent overleech, you get 50% of your life bar to reserve with auras too.

It makes you slightly weaker against 1shots yes, but only like 10% and for anything else, as long as you have good life recovery you take less damage overall.