I was testing something against the black sun boss, and i found that when he does his cutscene where he fires those black blasts in each direction, using profane veil will not work and you will still be hit.
Profane Viel mechanic is that it has 100% chance to dodge all hits inclusing dots [with talent point]. It works on all the other bosses such as harot, abomination, Husk of Gaspard etc, but not on black sun.
Makes me think its bugged as sometimes during monolith, i will get hit, even when i am in profane veil which should be impossible.
Ye its seems like a bad decision. But it may be bugged. Apprently entire interaction trees with fissure where not working with spine of malatos and now they fixed it. The profane veil and infernal shade are probably both not working [hellfire shade specifically]