General Chang's prototype Klingon Bird-of-Prey could fire its weapons while cloaked, a unique ability used in 2293 to frame the Enterprise-A for the attack on Chancellor Gorkon's flagship.
The vessel appears in Star Trek VI: The Undiscovered Country. Hidden beneath the Enterprise-A, it fires two torpedoes at Kronos One, making it seem that Kirk's ship has attacked the Klingon chancellor on the eve of peace talks. The conspiracy behind it joins Klingon and Starfleet officers who fear a future without their old enemy.
At Khitomer, Chang uses the invisible ship to batter the Enterprise and then the Excelsior while quoting Shakespeare over the comm. Uhura points out that the ship must still vent exhaust, so Spock and McCoy fit a torpedo with sensors meant for charting gaseous anomalies. The torpedo homes in on the plasma trail, reveals the Bird-of-Prey's position, and both Starfleet ships destroy it.