Siliconera brings word from San Diego Comic-Con that more karacters have been added to the roster of Midway's crossover fighter, Mortal Kombat vs. DC Universe. Specifically, the site confirms Jax and Kitana from the MK games are set to appear, along with DC Comics characters Green Lantern and the clown prince of crime himself, Joker. The site speculates that, since villains in MK vs. DC will be able to perform fatalities, Joker could conceivably kill Superman. We're not sure how happy DC would be about that, so don't get too excited.