When DotA 2 was ported over from DotA, Storm Spirit was a one of a kind hero. But in 2013, Valve released Ember Spirit and Earth Spirit and introduced them as the Spirit Brothers. Each spirit brother draws their powers from the 3 elements of Earth, Fire and Thunder. For a long time it was rumored that Valve is about to release the 4th Spirit brother and finally they did: Void Spirit.

Not much was revealed by Void Spirit except for the fact that he resided in the Void realm all this time. He claimed to have knowledge of everything as from the Void realm nothing escaped his eyes. He finished his speech by stating that it was time for him to join his brothers in battle.

Void spirit then proceeded to teleport himself to the Arena of The International. This teleport might be a very important ability as it seemed like he opened up a portal for himself similar to how Marvel's Dr Strange does.

That might be a very important and crucial ability for him much like Nature Prophet's Teleport.

Finally, he finished his bit by pulling out a very cool looking double sided sword. This might be an indicator of him being a melee hero. He is likely to be a carry or utility as Valve doesn't usually release two supports together.