On this week’s episode of The Flash, it’s a superhero team-up for the ages! Savitar and Alchemy take a backseat for the CW’s giant all-star crossover. Barry and the S.T.A.R. Labs crew are joined by the Arrow team, the Legends of Tomorrow and Supergirl! What threat could bring all these heroes together?

Previously, on Supergirl

This is it! The crossover we’ve all been waiting for since Supergirl came to the CW is finally here. If this episode is anything to go on, we’re in for a special TV event. The Flash kicks off the mini-saga in stunning fashion, bringing a perfect mix of laughs, fights and drama. While this season is improving, “Invasion” gives a needed, fun boost that also advances the Flashpoint fallout storyline.

A ship with aliens that would “give Ridley Scott nightmares” crashes in Central City. Barry realizes that it will take more than his own team to deal with this new enemy. Even though Wally wants to put his new speedster powers to the test, he’s talked down by Iris and Joe, given the threat the Dominators present. And this episode definitely paints the Dominators as aliens that do not mess around, as seen through historical footage, their effortless kidnapping of the President and their super-creepy design.

So who better to fight aliens than another alien? Even though Cisco is still pissed off at Barry for inadvertently causing his brother’s death, he puts their differences aside long enough to grab Kara from Earth-38. Throw in Team Arrow and the Legends and you have, as Felicity put it, “best team-up ever!” Just seeing these characters interact put a huge smile on my face, especially Kara who is meeting most of them for the first time. Their training session is particularly great, as she wipes the floor with them. Even the stoic Oliver needs a few minutes to catch his breath!

But Barry’s Flashpoint actions catch up to him. Cisco reveals his timeline shenanigans to the entire team, who are understandably upset. To make matters worse, Stein and Jax intercept an ominous message to Rip Hunter from Barry 40 years into the future. Future Barry says that he messed up the timeline and not to trust anyone, including Barry himself. With the President in danger, there’s no time to argue. So Barry and Oliver stay behind while the rest of the team goes to the rescue.

But it’s a trap! The Dominators use a device to control the heroes, leaving just Flash and Arrow to fend them off. This battle is one of the episode’s major highlights, putting the duo at a serious disadvantage where they need every trick to survive. Wally helps a bit before getting shut down by Supergirl, but Flash draws her away. They race to the device’s location for a stunning face-off. With Flash dodging Supergirl’s heat vision, running up buildings and trying everything he can to hold her off, the show reaches heights not seen since the team-up against Reverse Flash. It’s pure comic-book magic.

Barry uses Kara’s speed and invincibility to his advantage, letting her phase through him to destroy the item and set the heroes free. The good guys may be back together, but they’re not safe yet! The Dominators teleport Sara, Ray, Diggle, Thea, and Oliver to an unknown location, to be revealed on Arrow.

So far, with only one hour of television, “Invasion!” is everything that I wanted to get out of this superhero team-up. I can’t wait to see the rest!

Assorted Thoughts:

– “Barry, is there something I can do for you? Another evil speedster I can help with you with?” “….actually…” Ollie and Barry’s relationship is great.

– Ollie: ‘They’re calling themselves the Legends.” Speedy: “Egotistical, but catchy.”

– Flying and burning your own logo into the ground is a convincing way to prove you’re an alien!

– Kara has no idea how to react to Mick. It’s hilarious.

– H.R. gets the best one-liners. “I would be gone faster than humor in a Liam Neeson movie.” Despite this sentiment, he agrees to train Wally at the end of the episode. I’m sure this will go well.

– The woman appearing in Stein’s visions is his daughter, Lily. But did her sudden existence come from Flashpoint or the Legends’ time-traveling?

– Stay tuned later this week for an overview of the entire crossover special!