The main gimmick is Gravity Barriers. Make sure to bring at least 3 NGB monsters to move around freely. When you defeat every monster with the Skull, they do a volatile blast that heals poison. Since the main source of damage is the poison from the boss' first turn and mobs, focus on mob clear. Don't bring a lot of dupes on your team since Naga has a 5000 damage Infected Mist (Without Rage).