Pathfinder: Wrath of the Righteous

To easily defeat him, take a Venduag or any other ranged weapon. Leave the rest of the squad in another room, while you shoot at the elemental and run to the table to the right of the entrance. Just run in circles around the table and shoot. Do not try to fight him in close combat, this will most likely result in failure. A few dozen laps and the trophy is yours.