This is without a doubt the best episode of the season so far. With the added bonus of welcoming back Oliver Queen to the show, the episode dug deep into Multiverse lore and delivered an exciting and action-packed storyline.
The plot centered around the birthday celebration of Barry, where things unsurprisingly took a turn for the worse. The villainous returned to wreak havoc, and the heroes were forced to team up with Oliver returning to help out.
The action scenes in this episode were top-notch, and the chemistry between Oliver and Barry was great. Oliver Queen's return to the series was also a highlight, and fans of The Flash and Arrow will undoubtedly enjoy this crossover episode.
However, the biggest problem with "It's My Party and I'll Die If I Want To" is that it felt a bit rushed and cramped. With so much going on in the episode, it felt this could have been the arc for the whole season, not just one episode.