After rehearsals off New Guinea, "Mustin" sortied for the assault on Luzon on 9 January 1945, and for the next month fired in support of land forces, joined in repelling enemy air attack off Lingayen, and made antisubmarine patrols. She operated in the Philippines, aiding in movement of reinforcements until 2 February, when she sailed for Guadalcanal, off which she joined the 5th Fleet, serving as antisubmarine patrol ship while awaiting the beginning of the rehearsals for the Battle of Okinawa.