The Void is a purple radiated zone at the core of the world.
Currently, it is impossible to get to the void with mining cells, tnt, escevators, ect. since the top of the void is covered with End of the world blocks, which can only be broken by using a block phaser to remove it and replacing it with another block. This will delete the end of the world block and it is impossible to get back. If you fall into the void, you will only die if you touch the edge of the end of the world block, so by removing a 3x3 area you can walk around without dying. to get out of the area you phased out, you could place a block where the end of the world was to climb out.
Because of this, the Void is not a Biome of any Creativerse gameworld.