7. “Invasion!” – Season 5, Episode 8
It’s hard enough to balance a crossover among four different shows (Arrow, Supergirl, The Flash and DC’s Legends of Tomorrow), but “Invasion!” does this and more as it succeeds in telling a moving 100th episode. In the mix of battle between the heroes of the Arrowverse and the Dominators, Team Arrow (Ray Palmer, Sara Lance, John Diggle, Thea Queen, and of course Oliver Queen) are sent into a hallucination where Oliver never went onto the Queen’s Gambit.
There are a few positives that spin out of this reality, like Oliver’s parents still being alive and Laurel preparing to get married to Oliver. As the team interacts with this false world, they realize this isn’t their reality and their old memories start to seep through.
Even though in this reality the team have regained what they’ve lost they also see how they’re struggles have made them into the people they are today. It’s an episode that not only highlights Oliver’s journey, but also his teammates that have grown to become their own heroes.