Cloud City 4-21 is the twenty-first level of Cloud City. To pass this level with three stars, you should pop all pigs and score at least 68,000 points. After Han was frozen by Darth Vader, Lando tried to help the flock. His ability is shooting 3 lasers blasts in different angles once.
Send the first Lando through the bottom-left pig. Once he pops the pig, fire the blaster just below the rightmost pig. The ricochets laser blasts should slice the chains above the level, and falling debris should pop the pigs below.
Zoom out and send Lando towards the top pig. Shoot the wood plank on the rightmost structure quickly to wreck the right side of the level. Lando should hit the top pig and falling debris should pop the pigs below.