Omicron Squad was a team of Rank 4 Soldiers comprised of Specter, Wraith, Daemon, and Shade, and formerly led by Omega. They are supporting protagonists in Xionic Madness 4.
According to their bios in Xionic Madness 4 Part 2, the team led 52 successful missions under his command. Specter apparently became the leader of the squad after Omega left the group.
Xionic Madness 4 Part 1
The group is briefly seen hiding from Kary after she destroys the Overseer's shuttle. Shortly before the episode ends, they decide to move into action.
Xionic Madness 4 Part 2
The team reappears to save Omega and Xero from the zombified soldiers. Despite being grateful of their hospitality, Omega warns the team that they are likely to die if they continue pursuing against Kary. However, they state that they would rather die than betray their former comrades again, to which Xero praises them for. Without hesitation, the squad manage to provide backup for both Omega and Xero by shooting down several zombies.
The squad is last seen destroying a building that covered Omega from Kary's blast, causing them to be killed from the resulting impact.