OMAC Base is a Level 27 mission and a Tier 1 Duo.
The Duo requires Level 30 for access and rewards 2 Marks of Victory for players with a Combat Rating between 30 and 53. Players with a Combat Rating higher than 53 only receive Loot items from the Duo.
Locating the hidden base, Batman sends Fire and new heroes while the Joker sends Killer Frost and new villains to shut Brother Eye down. During the mission, Fire panics and Killer Frost flees leaving the heroes or villains to face Brother Eye alone.