Black Mercy

What it is
Black Mercy is a plant that is that creates a dream of a person's perfect life. They are harvested by Mongul. They tap in a persons pleasure centers of their brain. They have been seen to be used on Hal Jordan, Oliver Queen, Clark Kent, Bruce Wayne, and even the farmer himself Mongul. When someone discovers this reality is fake (they notice somthing wrong), or in other words they know their lives aren't this perfect.

Worlds they have created
Superman: His father Jor-el's prediction was proven untrue. He is married to a composite of Lois Lane and Lana Lang with two children. In the misdt of this Kryton is going into politcal upheave. His cousin (who would be almost 16 years older than him now) is attacked by anti-phantom zone protesters.

Batman: In this dream young Bruce's parents' murder is foiled. He grows up and has a wife, Bette Kane, and a daughter.

Mongul: Mongul kills the people he is fighting Wonder Woman, Superman, Robin, and Batman and goes on to conquere the universe.

Green Lantern: Hal's father never died nor did his mother. Coast city was never destroyed. Sinestor never turned evil and is his mentor and friend. They show the Green Lantern Corp fighting an unknow man possessed by Parallax. His family is together happy and he is dating his High School sweetheart Jen.

Green Arrow: Ollie is married to Sandra Hawke and has a great relionship with his son Conner. He has at least three kids. The titans are still together in their a orginal roster. His idenity is publicly known.

Unknown: He is superman

Unknown: A family man

Unknown: Won the Lottery

Flaw
The worlds are temporary and people always break free. Either the plants lose their grib. People may realize it isn't their lives or life isn't this perfect. It is possible it doesn't work because desires are empty.