Steel Essence Farm Guide
Steel Path missions (excluding RJ and archwing) spawn an Acolyte enemy every 4-7 minutes that drops 2 SE, affected by boosters. If you dont have good builds for Steel Path yet you can do the 6 daily incursion missions in the alerts tab, which give 5 SE each on mission completion.
Steel Path Void Fissures are an ideal farming method. Each opened relic give 1 SE at the end of the mission. Endless mission type fissures, like survival or defense, give a stacking booster per relic opened, which affects the SE dropped by the acolytes. This boost maxes out after 18 opened relics. Void Cascade Omnia Fissures are the preferred mission type for this as they have very fast rotation times allowing quick booster build-up.
Steel Path Perita Rebellion missions are the fastest way to get Steel Essence, if you have builds that can clear orders quickly. A Commandeered Warframe enemy spawns every 3 completed orders that drops 2 SE affected by boosters, and you can get from 4 on average up to 6+ spawns per ~14 minute mission, much faster than waiting for acolyte spawns every 5 minutes in normal SP missions.