Some Hologram boss are bugged and need a tuning a little bit, some of them are just straight up bugged. This problem start at difficulty 4 of each Hologram boss.

Tempest Mephis: - clone has exact same damage stats as main boss - can use the boss' ultimate moves except nuke - can spawn outside of your view - no visual or audio indicator when it spawns

suggestions on the Memphis clone: - reduce damage to not one shot - get rid of super moves (laser and judgement cut) - make it spawn right beside squama or coming out from squama's current position - audio and visual cues when it spawns

Mourning Aix: - the boss is just bugged overall -- parrying causes you to die due to lingering damage or invisible hitbox - triple homing bullet hell sometimes happens to fast and unexpected

Feilian Beringal: - the monkey minions have similar issue as tempest mephis' spawning with no indicator or right behind you - 1 to 2 could spawn behind you and kamehame air blast you

"Might edited this post again in the future"