Injustice 2 has dropped a new trailer for Raiden. He's part of the Fighter Pack 2 DLC, which also includes Black Manta and Hellboy.
Raiden is a mainstay of the Mortal Kombat series, and describes himself as 'the true god of thunder' in his pre-fight sassing in this gameplay trailer. There's a lot of lightning on display here, and it looks like you can use Raiden to set up a lot of devastating combos (which isn't so great to play against, mind you).
It's also revealed that Raiden will come with a Black Lightning premiere skin included with the ultimate edition, which is pretty cool. Raider will be available some time in October, so look forwards to that if you've already got the Fighter Pack.