I did a Purge level IV in single player. My test base was a pyramid connected to a hallway of three gates. The hallway was packed with fighters and the pyramid had archers above the anti-climb. The purge spawned behind the pyramid and huge mobs went up the incline and attacked my archers. The mobs ignored the hallway with gates and I had to agro mobs over to my fighters. I killed the main enemy but his body disappeared and I couldn’t get the key. At level IV my framerate was starting to chug. I’m on Xbox. The mobs look bigger than the battles on AC Odyssey.