The advantage of assassin works for the entire combat? or just surprise round?

@JeremyECrawford The advantage of assassin, against creature that hasn't taken a turn, works for the entire combat? or just surprise round?

— André (@als260502) September 26, 2016

Assassinate works only against a creature that hasn't taken a turn yet. #DnD https://t.co/C1bBoaOHb5

— Jeremy Crawford (@JeremyECrawford) September 27, 2016