The Voice in the Darkness is a non-corporeal entity that lives in the Amulet of Shadows and The Ether. It grants incredible power to anyone wearing the amulet, but also slowly drives them insane or possesses them. Some powers granted by the Amulet of Shadows include flight, invisibility, and the ability to make non-sentient hostile mobs ignore you. The Voice in the Darkness is the most powerful demon of the Nether also named Dante which means hell. In the end times, he and Herobrine shall merge to free a uamoutable force from his prison, in which it will then discard them, and they will fight with the good guys.
The Amulet of Shadows is very powerful, except for the side effect of causing possession and/or insanity. The Amulet is currently worn by Jack. Also, it is impossible to remove the Amulet on your own, as whenever you try the Voice knocks you unconscious.
The Voice in the Darkness is the main antagonist of DoM. It is responsible for commanding the Eye of Ender and the Legions of the Nether in a plot to invade the world. It also seeks the components of the Destruction Amulet to end the world.
Aftermath Minecraftia canon
After his apparent 'defeat' during the events of the invasion, he was sent back into the void to recuperate. He waits alongside his most trusted minion, waits for the chance to attack and finish what he started, and retrieve his beloved Amulet from the hands of Steve.