Even with the April 16 release of Injustice: Gods Among Us just weeks away, there are still two playable combatants yet to be formally revealed in NetherRealm's fighting game lineup. Big as the DC Comics universe is, it seems like almost anyone could join the current cast of two dozen heroes and villains including Superman, Batman, Wonder Woman, Lex Luthor, The Joker and others, but from the looks of two new costumes in the Xbox Live Marketplace, it appears Ares and Killer Frost could be set to join the fray.Both characters were apparently playable as part of a the game's 'S.T.A.R Labs' mission challenges when CBS got hands-on with the title last week (although, so was Martian Manhunter, among others, in IGN's trail) and now Wonder Woman's God of War antagonist and Firestorm's frosty femme fatale are available to purchase alongside an array of other confirmed character costumes and items on XBL.

If the characters do indeed get confirmed as playable, they'll both bring something new to the current lineup. Killer Frost's elemental ice attacks seem like something Aquaman would dread, while Ares' magic moves would give Superman some grief.

Even if Ares and Killer Frost are the final two fighters set to join the game, it's still unknown what their delivery system will be. Unlockable? DLC? Available immediately? More importantly, will Ares have an alternate skin featuring his sweet medallion? We will keep you posted.

[Via Joystiq]