虚魂术（Voidbinding）is presumably a magic system on Roshar. It is referenced once, in the Ars Arcanum of the Way of Kings, which says that there are ten levels of Voidbinding, like there are ten levels of Surgebinding. However, the writer of that Ars Arcanum states that the ten levels of Voidbinding may be different.
One of the most common powers associated with Voidbinding is prophecy and foresight. According to the ardents even the Heralds denounced its use. Whether or not this is true or a myth that has cropped up over the millenia is yet to be seen. Regardless, in Vorin nations any type of future prediction was feared and avoided because of this belief. The ardents even worried that Dalinar's visions were connected to Voidbinding, although since the visions come from Honor, their belief was inaccurate.
The Vorin reluctance to guess the future led to the rise of games like breakneck, that don't require directly guessing the future. Some are even distrustful of stormwardens as well, since they predict when highstorms are going to occur.
Some speculate the sphere Szeth takes from Gavilar in the prologue is related to Voidbinding