Voidwalker was a powerful soulcraft that was developed by Lord Knight Falken, and allowed him to freely traverse Void at will, earning him the name Falken the Voidwalker. This powerful ability made Falken completely immune to Void, letting him enter and exit Void freely, as well as allowing him to directly combat Void during The First Void Insurrection. Using this soulcraft, Lord Knight Falken managed to defeat the Void Avatar Cyratel and seal Erebus within Void, a testament to the soulcraft's power. However, Voidwalker takes a hefty supply of Anima to sustain over long periods, and it's due to this that after the defeat of the Void Avatar, Falken could no longer power the spell and he was consumed by Void.
As Lord Knight Falken was the only user of the soulcraft, with his fall at the hands of Void the ability was forever lost.
There have been multiple attempts by many over millennia to recreate the art, but all attempts have been unsuccessful.