Void Sanity reduces susceptibility to insanity. Insanity chance is divided by <value>, e.g. 10.

Void Sanity also reduces Insanity gain from certain sources, such as interacting with a Void Gate and being sucked into the Void, and having any amount protects against some rarer mental effects. It also makes being in the Void safer in general, by preventing Dimension Overload.