When the Patriarch spawns, he will walk slowly towards the team's position. Once he gains sight, he will cloak and charge at a random player.
Once he becomes visible, the team should unload on him while keeping out of his melee range. He will repeatedly cloak and switch targets, going after players who are isolated or furthest away from his position.
Every few seconds he will use his weapons to attack, and he will pick between the Minigun, Missile Launcher or Mortar based on what phase he is on.
Fighting him in an enclosed location with a low ceiling will prevent him from using his devastating Mortar attack.
He will use his weapons more frequently the more damaged he is.
When his health drops to 42.5%, he will begin summoning lesser ZEDs to aid him. When his health drops to 35%, he will cloak and attempt to flee from the team.
Once sufficiently far away from the team, he will inject himself with one of the three healing syringes strapped onto his leg, healing based on difficulty and number of syringes left. Refer to the table above for specific numbers.
Once he has healed, ZEDs will stop spawning. He will then cloak and sprint back towards the team.
If a player kills the lesser ZEDs while in his line of sight, he will target them first.
Choose a location with many obstacles to block his line of sight to easily dodge his missiles and minigun. However, on Suicidal and Hell On Earth difficulty, there's a high chance that the Patriarch can walk while firing his minigun - Continue moving, even if you are around a corner, just to be safe.
Never stand still and do not bunch up together as he can kill multiple players with missile/mortar splash damage easily or he will perform the clothesline attack if too many people are in close proximity to him.
It is possible to kill him before he has a chance to flee and heal, by trapping him in an enclosed room, therefore ending the fight prematurely.
It is highly recommended for each team member to purchase either the HMTech-101 Pistol or a Katana before this fight begins, as it will allow for the team to heal each other throughout the battle or parry the Patriarch's attacks when he decides to target you.