Corto Maltese mission
During the Corto Maltese mission in 2021, members of Task Force X were sent to destroy the remains of Project Starfish. In the Battle on the Corto Maltese Beach, Javelin was killed by Corto Maltese Armed Forces, but before he died, he bestowed his javelin upon Harley Quinn, considering her the best fit to carry it.
Escape of Harley Quinn
Harley Quinn was promptly captured by Armed Forces and sent to meet General Presidente Silvio Luna. The javelin was confiscated, but after Harley killed Luna, she was interrogated by Mateo Suarez in a torture room, before escaping and finding the javelin on her way, further using it to escape.
Destroying Project Starfish
Harley rejoined the rest of her team, infiltrating Jotunheim. When the lab was detonated, she used the javelin to survive. Later, when Cleo Cazo used her rats to counteract Starro, Harley used the javelin to enter Starro's eye, killing the creature from within. After the mission ended, Harley returned to America with the javelin.