When Varnok was a little baby up in the aether, everything he touched was destroyed instantly. So the gods came up with a plan, they moved young little Varnok to the nether, where he could grow without hurting anybody and the Ghasts would protect him. But when Varnok grew up and learnt what the other gods had done to him. He grew with rage and planned to get revenge. Varnok had learnt some things in the nether and knew how to tap into people brains and control them. So he quietly returned to the aether and lured a god into his trap. then as this god he started to destroy the aether. After a fierce battle with the elder gods, he was defeated and his eyes gouged out, so he would never be able to control anyone again, and banished to earth.

While abandoned on earth, He created an Army of Creepers, and managed to create a portal back to the nether, where he collected the supplies to create a warp for all the people of earth to travel to the aether. And to destroy it themselves, without knowing he was there to guide them,

On earth he preys on the unweary, unsuspecting to do what he wants. He captures them using telekinesis and them sends them to work, destroying landscapes, houses, towns and even cities.

So next time you destroy someones things or possesions, know that you fallen victim of Varnok...