When Shao Khan and Darkseid entered a dimensional portal at the same time in their own universe they created a dimensional rift, which caused two universes to merge together.

This also led to Shao Khan and Darkseid to merge into one being known as Dark Khan. While the two worlds started to merge Dark Khan used rage to make heroes of both universes to battle each other, fuelling DarkKhan's power.

Dark Khan stayed in the shadows, but eventually Raiden and Superman found him. Using the rage against him they managed to separate the two beings from each other. This caused the both worlds to return to normal, but with Shao Khan and Darkseid being trapped in each other's words without their powers.