Challenge Mode/Superman Godfall/Expert/Challenge Battle 5

Doomsday is required in all matches of challenge battle 5. There are three possible characters you could choose: Doomsday/Regime, Doomsday/Prime and Doomsday/Containment. While Regime Doomsday is given by the Starter Pack, he is a silver card and thus has much lower stats and he has a poor passive. Prime Doomsday is a very strong card especially for new players, and he is always available for purchase (while Containment Doomsday can only be found rarely in Challenge Booster Packs and the Most Wanted Pack, if you haven't unlocked him from his challenge over a year ago; it is not practical to try and get him solely for this challenge), so he is the best to go for if you don't have a good Doomsday card already.