From publisher blurb:
In the ongoing war against super-powered criminals, terrorists, and villainous shadow organizations, the men and women serving the various Strikeforce teams have seen their share of casualties. Every team has lost at least one, and often multiple, members to death, permanent injury, forced retirement, or permanent psychological trauma. The oldest and most storied of the teams, Strikeforce One, has endured the greatest degree of personnel turnover due to retirements, injuries, and fatalities. Each team is designed to allow and compensate for losses. Thus, codenames remain the same even as the individuals holding them rotate in and out. Case in point with Strikeforce One, the first Alpha (the legendary hero, Victory) retired his post, passing on leadership to Athena Costas, also now retired. For now, the Alpha position remains empty. Along similar lines, the two people holding the positions of Iota and Sigma are not the first to hold those codenames; the previous Sigma died in combat, while the previous Iota went missing over two years ago. Omar Sandar holds the position of Iota, while Angela Santos-Cross holds the Sigma codename.
This PDF contains everything you need to know about the Strikeforce members, Iota and Sigma in the Amazing Universe Campaign or any other superhero campaign.