Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
While playing Nocturne you would like to open with you "Q" spell. Then cast your "E" spell and auto attack. (rinse and repeat). Across the map always use your ultimate (R) to save your allies before they go down.(inset your mom joke) Using your ultimate at the correct time can really change the game.