Krypton is probably the most famous planet in the DC Comics. The planet appears on the pages of the earliest comics about the Iron Man where it said that the Kryptonians began to possess a powerful intellect and superhuman strength as a result of evolution, and then the planet exploded.
The second season of Krypton will include Flamebird and Nightwing. However, this is not Nightwing of the battfamily everyone knows about. This will be a Kryptonian God like Flamebird. They are similar to The Voice of Rao from the first season.
In the first season, Seg-El played by Cameron Cuffe united with his son to win over Brainiac. After his defeat, the General Zod came to power, erasing Superman from history.
Very few details are known about the second season and it is not clear yet whether the two Gods will appear as dragons or human-like creatures. Flamebird and Nightwing are reincarnated over and over again and look for each all their lives to tragically die.
In addition to these two characters, Lobo will also come to season 2. The second season will be released this fall.