The conversation between human and AI assistant.
[|Human|] Which episode did Daenerys Targaryen lose her dragon, Viserion, to a White Walker's spear?
[|AI|] The Night King, the leader of the White Walkers, threw a spear at Viserion, which killed him.
[|Human|] 
Which episode did Daenerys Targaryen lose her dragon, Viserion, to a White Walker's spear?