B737 pilot reported #2 engine vibration began prior to descent. Flight continued to a safe landing.

Narrative

ZZZ1 to ZZZFlight operated normally from gate XX out of ZZZ1. Followed by normal take off; climb and cruise. A few minutes prior to top of descent; a lavatory break was set up and prior to calling the Flight Deck to return back in; I heard the engine slowly spool back followed by heavy vibrations followed by and loud synchronous bangs. When I entered the flight deck I saw the captain had the #2 thrust lever set to idle. Every time the #2 thrust lever was increased; the vibrations and bangs would resume. The captain asked to run the QRC Engine Fire or Severe Damage or Separation without pulling the fire handle. Continued the checklist in the QRH while descending to FL270. At FL270; the captain already had the APU started and set the APU GEN to power the right side. We then proceeded to run the One Engine Inoperative Landing QRH checklist. After that was completed; the captain relinquished the flight controls to me and briefed the flight attendants and made PA to the passengers; while in the mean time I was coordinating with ATC to have us for a long final for runway XX into ZZZ and to have ARFF (Airport Rescue and Firefighting) standing by for us. Once; the flight attendants were briefed and the PA was completed; the captain took control of the aircraft and continued to fly all the way down to the runway. Landing configuration was Flaps 15; Autobrake set to 3 below MLW (Maximum Landing Weight). We stopped on the runway; I proceeded to select the Flaps to 40; ARFF inspected the aircraft with and told us that the #2 engine looked intact and had to fires; and that the brake temperatures we optimal. We proceeded to continue taxi to gate XY but still had a firetruck follow us just as precaution. Normal after landing flow was completed; followed by the shutdown checklist at the gate. Once the deplaning was completed; I did a routine walk around and found nothing that would indicate the #2 engine suffered any damage.We were promptly removed from the rest of the sequence which was supposed to fly back to ZZZ1 and headed to the hotel.