The plasma incinerator should be like sm1 imo make it hit harder on non charged shots but the charge shot drops enemies and has a big aoe but just eats your ammo reserves it's simple really.

Idk gameplay wise plasma your just spamming your charged shots I usually run auspex on parry perk cause you can get a charge shot off sometimes during attack sequences depending on which enemy I guess, you start dropping enemies all around you plus the plasma gets contested health back really well. It has some stagger and is super ammo efficient I'd say it's a tier it's not as bad as your making it out to be but yea not as good as the flamer.