Simulated Art.

If Legion were awake to see the progress of the era of conquest, they would be surprised to find that most of the things that happened in the simulation was real. If they had been awake, they would have been able to use the information in the simulation to their advantage. 

They have the First Sage to thank for that. Of course, Soverick's technique is extraordinary, even for Supreme Origin gods. But it still can't compare to what a world god who specializes in fate is capable of. 

The first sage tried to make the illusion as real as possible, so he used the information Soverick had and added a little information from his side to fool them. It had to be authentic, or it wouldn't fool them. After all, they were stupid, not blind. Even stupidity couldn't stop them from noticing a glaring vulnerability. Soverick proved this point very well.