Gossip Girl Season 4 Episode 7 (Gossip Girl s04e07) with title “War at the Roses” aired on Monday, November 1st 2010 at 09:00 pm via CW Network.
Here is summary for Gossip Girl Season 4 Episode 7 :

Blair is caught off-guard – and not in a good way – by a surprise guest at her birthday party. Having had enough of Chuck and Blair’s games, Serena and Nate decide to plan an intervention.