Daxamite invasion

The Daxamite Invasion was the hostile attack in National City, Earth Thirty-Eight by the alien race known as the Daxamates who had the goal of conquer the planet Earth and make it the new home for the Daxamites as well as sate Rhea's vengeance against Supergirl for turning her son against her.

Background
Rhea's son Mon-El didn't want her to destroy National City and was forced to join Rhea's team.

Queen Rhea tried to inspire Lena so she would be a member of Daxamite army. Rhea was impersonating to be a human. Lena was later forced to be a member of Rhea's team and the fiancée of Mon-El.