Atziri invulnerable

Finally made it to atziri chamber. But i got stuck at a phase which she keep spamming red thunder and expanding blood projectiles. She seems stuck in the animation (no movement at all), and i cannot deal dmg to her.

Blackcrow v2.0. Same with Lightless Serpent in abyss sublevels (the thing, that burrows and while moving in circles is immortal, even it's simply white mob) - it sometimes stucks in animation in invulneraility phases and can't die.

I hope, one day they will remove all invulnerability phases from bosses completely, they stuck too often to be a good "feature".