Clock King and Sportsmaster are able to escape from Power Girl and Harley Quinn by firing a short range ballistic nuclear missile towards Power Girl. The duo tracks em down and a second fight occurs in Central Park. Harley Quinn shoots em both with a gun to incapacitate them long enough for the cops to arrive.
Clock King complaining that Supreman and Batman doesn’t use guns is hilarious. They’ve gotten complacent with nice heroes apprehending them.
From – Harley Quinn Vol. 2 #13