Anti-Dalek Fluid Gun

An Anti-Dalek Fluid Gun was in the possession of a tourist visiting the Dalek Dome. When some of the Daleks escaped the simulation, he believed it to be part of the act, and held the device to the Supreme Dalek, asking it to exterminate him, with the Fourteenth Doctor insisting that it wasn't an act, and pulling him away from the Daleks. The boy, however, proceeded to splash the Supreme with a ray of water. (COMIC: Liberation of the Daleks)

Behind the scenes

 * The device can be recognised as a counterpart of the real-world "Dr. Who's Anti-Dalek Fluid Neutraliser" - a water pistol.