Arrowverse Crossover: 10 Most Awesome Moments From 'Invasion' (Part 1)
8. Dr Stein's Daughter
While the episode has lots of fun moments, it also finds plenty of room for drama too. There's the ongoing arcs of Wally trying to become a hero, and Cisco not being able to forgive Barry. The strongest, though, is how Professor Stein has been affected by the new timeline.
For a start, it's just nice to have him firmly back in the fold on The Flash, since he was a strong supporting character before leaving for Legends. But it also provides the episode with some necessary emotional heft - which was nicely played by Victor Garber - as he discovers he has a daughter now.