I'd like something like this:
Last 10 minutes of the episode. The Pierces have just finished dealing with some fukkery from
along with the general madness of Freeland and are settling in for the night. Jen is out smoking on the roof, Nissa is in bed struggling to sleep, and Jeff and Lynne are up talking and trying to figure out how their lives came to this. There's some old school soul music playing (maybe "A Change is Gonna Come?" idk). Suddenly, the ground trembles like nothing they've ever felt. The house starts to shake and everyone tries to find cover. Once the coast is clear, Jeff gets up and peers out of the window. He hardly believes what he sees.
The sky is bloody red.
Very next scene, Black Lightning, Thunder, and Lightning are suited up and in the streets helping keep order with Gambi on comms and Lynne on her way to the hospital. The quake did a number on Freeland, and between the injured needing rescue, the looting, and random outbreaks of violence, it's all hands on deck. We see Lightning helping a family through some wreckage. She comments she wishes someone knew what was going before being knocked into the air. She peers up at her attacker; it's some kind of black creature made of a substance she can't identify. She attacks, and while the creature is hurt, she doesn't do nearly as much damage as someone with her kind of power should.
More creatures appear, and Team BL struggles to fend them off. The Pierce family is clearly tired and unsure of what they're even dealing with. Black Lightning echoes Jen's comments, yelling to Gambi to tell them if he's found out anything about this.
"He wouldn't know. This is beyond him."
Just then, a red streak appears and knocks away some of the black creatures; just enough for Jeff and Jen to blast the rest away. The Pierces look to see their new ally: an older man in a red suit with a lightning bolt in the center. It's the Barry Allen of Earth-90. "Your friend isn't going to find any information about these things. They're not from this Earth."
"This Earth? What do you mean 'this Earth?' Who the hell are you? What's going on?" Thunder asks.
"His name is Barry Allen, otherwise known as The Flash. He's the last survivor of a doomed Earth - a hero like you, Anissa. Jennifer. Jefferson." The Pierces turn and are greeted by the Monitor. "Your world, your very universe, is under attack. The eradication of all you know is inevitable, unless you come with me. You all have a role to play in the coming Crisis."
We see the Pierce family's worried faces before smash cut to the "Crisis on Infinite Earths" logo. End episode.