9. What Happens?
After building towards it all season, 'You Have Saved This City' finally saw Emiko Queen and the Ninth Circle launch an all-out assault on Star City. However, her plans hit numerous bumps as the largest variation of Team Arrow to ever exist (thanks to the returns of Laurel Lance, Curtis Holt and Ben Turner) showed up and thwarted them on multiple occasions.
This all led to a showdown between the Queen siblings, during which Emiko began to mellow. Unfortunately, before she could make amends for all that she had done, she was killed by other displeased members of the Ninth Circle (before her body was presumably destroyed in a subsequent explosion).
Reflecting the present-day events in more ways than one, the flash-forward narrative dealt with a terror threat of its own as Roy, Dinah, Felicity and Alena teamed William, Mia, Connor and Zoe in a successful bid to stop Galaxy One.
Before any variation of Team Arrow could really celebrate, they were faced with the reality of a certain character's departure, resulting in both narratives leaving us on an overly emotional note.
While Oliver and Felicity officially left Team Arrow for good in the present day, the return of The Monitor signals the former's impending sacrifice - an event that causes ripples so significant that they are still being felt in Star City over two decades later.