This issue went on sale four weeks after its solicited date, with different content than what had been originally solicited (the solicited content ended up in #14). This change was announced by a press release on 2006-09-19. The inset of Terra came from promotional information about the character, and ended up being used as the cover of Terra (DC, 2009 series) #1.
This issue has variants:
Supergirl [Kara Zor-El]; Captain Boomerang, Jr. [Owen Mercer]; Nightwing [Dick Grayson] (cameo); Terra [Atlee] (intro); Empathosaur (intro); Streaky (unnamed, cameo)
Synopsis
Kara attends a rave with a superhero theme and enjoys herself. Suddenly, the wall blows in, as a result of a fight between Terra and an Empathosaur. She reluctantly joins the fight, but the creature senses her emotions, and causes her to flee temporarily. But she returns and fights, even when the creature confronts her with images of her father. Together with Terra, they defeat the creature, returning it to the earth. Supergirl is somewhat intimidated by Terra, who seems to have her act together. Later, she discusses this all with Boomer, who invites her out for a night on the town.
Story-wise, this issue occurs between issues 10 and 11. At Wizard World Los Angeles on 2007-03-17 on a panel, Conner revealed that in the rave scenes Palmiotti and Conner placed many of their real-life friends.