Jacques O'Lantern is a boss in the new Borderlands 2 DLC T.K. Baha's Bloody Harvest DLC.
He can be fought by going to The Pumpkin Patch and turning on the spigot found on the Southern wall.
Fighting Jacques O'Lantern
He will largely stay to slam attack you with his fists. He also possesses an Eye Laser attack he will use.
He will move in toward you and punch you. This is his basic attack.
He is able to charge at you from across the arena. He will lower his shoulder and come at you.
He can also lob a pumpkin into the ground. This cause a number of Pumplings to spawn. Look out for the ones marked with a White Exclamation Point. These will run toward the Kingpin, latch on and heal him. Any others will charge you.
He may also cause white circles to appear on the ground. These act the same as the Slow Spell Trap, dazing you and severely hampering your movement.
When his lifebar is depleted he will become: The Jacques O'Lantern's Head
This boss has numerous Pumplings running around the area. If you they get on him then he will start regenerating health.