bad4youLT's post in Tempestarii Turrets: What are they and how do I obtain them? (Mission Spoilers) was marked as the answer
As of yet no way to obtain and prob won't be obtainable as those were most likely added to Tempestarii to avoid players possible terrible loadout .
bad4youLT's post in Is It My Imagination, Or Do Assassination Bosses Spawn More Frequently On The Steel Path? was marked as the answer
Because they are , all assassin spawn rates in steel path have been increased .