Utilizing identical dresses and masks at the Empire Hotel ball, the conspirators successfully impersonate Serena to humiliate her publicly and drive a wedge between her and her family.
"Gossip Girl" The Witches of Bushwick (TV Episode 2010) - IMDb
The trio manipulates Serena’s communications by swapping her SIM card, allowing them to impersonate her via text and alienate her from both Dan Humphrey and Nate Archibald.
Blair ultimately chooses her own identity and drive over the relationship, leading to an enlightened agreement with Chuck that they will find their way back to each other in the future. 3. Consequences and Climax