Complex sentence: Mirage is then hired on as a member of Boomerang and Owl's Sinister Sixteen, a team assembled to distract the Chameleon's forces while Boomerang steals from him.
Split into simpler sentences: Mirage is then hired on as a member of Boomerang and Owl's Sinister Sixteen. The group was assembled to distract the Chameleon's forces while Boomerang steals from him.