In a mechanic unique to Knights in the Nightmare, a monster's Element Gear is displayed after the target has been launched by certain skills. Turning this gear will change the monster's element. Turn it clockwise to cycle them in this order: Neutral > Fire > Ice > Lightning > Sanctity > Darkness.
Some skills that cause the Element Gear to appear are Archer's Chaos skills, and most abilities available to Priestesses and Wizards. However, launching doesn't work if an enemy is performing a Bullet attack at the same moment. In addition, monsters without a designated movement type, such as Mimic, Dryad and Saber families, are impossible to launch.