This was a very good episode of Arrow with a lot of mystical and magical elements towards it. We even got to meet Constantine on the show, so, let's talk!
Constantine and Bringing Back Sara's Soul
I never felt the need to watch Constantine, but since his show was cancelled he has become a character in Arrow. We meet him in a flashback where he and Oliver obtain a magical object and after Oliver helps him, Constantine says he owes him one.
Bring it back to present day, and we find out that when you are resurrected from the Lazarus Pit, you want to kill the person who had killed you. Thea's killer is Ra's al Ghul, which is why she is fine for the most part. Sara's killer is Thea, so she tries to kill Thea multiple times in the episode. Instead of them having to put Sara down, Oliver calls in his favor from Constantine.
Constantine performed a mystical ceremony to literally retrieve Sara's soul. Constantine, Oliver, and Laurel went into the other world where the real Sara, who represents her soul, is being drowned in the Lazarus Pit- where they had to fight off a bunch of League members. It looked like some type of monster that was grabbing Sara, like an octopus or something. They got Sara's soul back and she is actually back to life now. Something to note is that before Constantine left, Oliver asked for advice and he told him to leave town, which is some interesting advice. Constantine and Damien Darhk are both magic users and Constantine could be a real help in the future. Seeing Constantine on the show was really cool and I'd love to see him pop up once in a while.
Diggle and Lance Team Up
They had some good chemistry as they went to figure out what exactly Darhk gave Lance. Darhk tells Lance that H.I.V.E. hired an assassin to take out Diggle. He says Diggle was competition for H.I.V.E. in Afghanistan, and that he was a crime lord they had to take out. Lance shows this to Diggle and he was devastated, but happy to know. Looks like there is more to Diggle's brother than we think. What if he worked for H.I.V.E. as a villain but then betrayed them and was hunted down and killed? It's hard to say, but that seems like a pretty damn good theory.
Oliver and Laurel Heal their Issues
Since the first episode in Season 1, Oliver and Laurel have never really gotten along and this was the moment we have all been waiting for when they finally make up. Oliver hasn't always been the fairest person to Laurel, so he went out of his way to fix things with Sara and Laurel is forever grateful.
Ray is Alive
For a while, Holt was trying to decrypt the final words of Ray Palmer that he'd sent to Felicity. Ironically, when they decode the message, he says he's still alive. We already knew that he was shrunken, but as the promo for the next episode suggests, he is being held by none other than Damien Darhk (*cue dramatic music).
When will see Constantine again?
Well, don't expect to see him anytime soon. He is a very busy guy as he barely even had time to film this episode because he is filming a movie and is on a Broadway play. We should see him at least one more time this season because him and Damien Darhk are both magic- wielding people so having Constantine in the universe now, this is a given. We will probably also see him on Legends of Tomorrow at least once.