Look, I get it, it’s a way to split phases and provide some degree of spectacle the first time around. But the designers really need to understand, that if these bosses actually have worthwhile loot, then they are going to be fought more than just one time and it gets really old the more times the boss has to be killed.
In my opinion, having enemies or bosses that become immune to damage for a set duration that is outside of the player’s ability to influence is straight up infuriating and does nothing but waste our time.
Captain Haunt as an example, was a good boss because even though he had immunity phases, how quickly the phase is canceled is up to the player’s own ability to execute the strategy of the fight.
But stuff like anointed militants, Killavolt’s random teleport away and immunity aura plus showboating, or Tyreen’s back to back attacks that simultaneously damage the player and render her immune to damage/take her outside the arena? Absolute garbage that kills the pace of the fights and makes them unfun to fight.