+make the patrol escalate as you keep doing objectives, bigger and bigger things come out to counter you.. or maybe you kill enough mercenaries Taskmaster shows up on the Map.
+random timed events happen.. Tachyon rift disruption.. collect rifts stop enemies from leaving the area that come out of the portal, until the incursion is fought back.
+LootBots that when killed teleport us to a City Scape that has a boss fight.