Date: December 16th 2015 Episode: "She Gets Revenge"
To start episode 10 of American Horror Story: Hotel, The Countess and Donovan have parallel scenes with Valentino and Natasha. In the end of the scene, Donovan has shot Valentino dead and The Countess has shot Natasha dead.
For her slaying scene (literally) Lady Gaga wears a black silk gown contrasted by her high volume platinum blonde updo.
Lady Gaga's dress comes from Vivienne Westwood's Spring 2015 Ready-To-Wear collection, look 10, and is not available for purchase online.
More HQ Screen Captures from Episode 10 of American Horror Story: Hotel are available here.