Interaction of yellow lifeforce boss and delirium feels bad

This boss often does a multistep attack where it becomes invulnerable fading in and out and leaping after the player. When there is delirium on the map each of those individual leaps will potentially be replaced by a longlasting delirium attack further prolonging its invulnerability phase. It actually happens quite freuquenty that the boss instantly starts this whole attack again after one just ended. Ultimatively it just ends up being quite frustrating having to wait forever until this guy can actually take damage and it feeling tied to randomness to that extent.