They've already been introduced - Olivia Pearce, CEO of the super-weapons company Spheric Solutions, and the inhuman Zanni.
They're the last of the " Cirque du Sin ", criminals Nightwing stopped with Batman
back when he was Robin. The Zanni was the power behind, and Olivia was the group's " Colombina " (commedia dell'arte
references both.)
They've been making things happen in Blüdhaven - Pearce's helped normalize
walking tanks as police equipment and the Zanni's inflicted
fifth-dimensional travails on Nightwing.
Their endgame is the world as circus, with Dick their " ringmaster ".
( What this Annual's story establishes is why they want that. )