This multiverse is relatively young. However the universe it came from is very old. The Great Old Ones were the dominant sentient species that developed in the universe and evolved so far that they became almost as gods themselves. They ultimately evolved into non-corporeal form. During this evolutionary process they also became almost immortal and in doing so lost the ability to procreate.
Then, against all odds, two children were born. It’s not known how they were conceived or who the parents were. They were named Satania and Jeohab.
The Great Old Ones attributed their survival and evolutionary success to following and achieving a balance in everything. They hadn’t brought up children for many millennia and wanted to educate them about the Balance.
They found a planet in a remote backwater of the cosmos that was relatively undeveloped but perfect for sustaining sentient life. Here, on FirstWorld, they established an experiment for the benefit of the children.
They brought two species to Earth from elsewhere in the galaxy where their planet was dying. One, the elves, was assigned to Jeohab and was designated to Law. The other, the dwarves, was assigned to Satania and was designated to Chaos. An indigenous species, humankind, was genetically enhanced and given free will to choose its own pathway. The children were supposed to learn from observation and strategic interference with only their respective race.
The experiment lasted 6567 years but over that time the children got bored and lost interest. The Great Old Ones made a further evolutionary leap and left our universe. Before they left they created the wizards to keep an eye on their experiment and serve the Balance.
Unknown to the wizards, they had also buried someone or something evil deep under the mountains.