Batman vs. Doom vs. Thanos
A mysterious figure appears before Bruce telling him that he knows who killed Bruce's parents. He gives Bruce a complete biography of Thanos and tells Bruce to spend the next month preparing to defeat Thanos and after a month, he will be teleported to Thanos' headquarters. If Batman defeats Thanos, his parents will be returned to life. But he warns Batman that Doom is also gunning for Thanos and if Doom takes down Thanos before Batman, Batman gets nothing. He gives Batman a bio on Doom as well.
A minute later, that same mysterious figure appears before Doom telling him that by defeating Thanos, Doom's mother's soul will be released from Hel. Doom also gets a month and a Thanos bio, and also gets the warning and bio on Batman.
Thanos knows nothing of these plans.
A month later, they both get teleported in front of Thanos' stronghold, and in front of each other.
Batman and Doom, the two premier intellects in comicdom with one month prep against each other and Thanos, who is unaware of what's going on until an alarm is tripped.
What happens?