The phrase "masterful piece" refers to something that is exceptionally well-made or skillfully executed. It describes something that displays a high level of mastery and expertise in its creation. Full definition
MUBI has teamed up with Mondo to create New Art for Timeless Cinema, a series of newly imagined artwork for masterful pieces of cinema — starting with Olivier Assayas and Maggie Cheung's meta, modern class. (vodzilla.co)
I Saw the Devil is an absolute masterful piece of horror cinema that is downright brutal and dark as all hell, and now it's headed to the States. (themissingreel.com)
Elle is a flummoxing, aggravating, possibly masterful piece of filmmaking that will leave you reeling. (maddwolf.com)