The Brain or the Will of Valmar, is the final and most dangerous piece of Valmar. Through his possession of Pope Zera, the brain works to re-unite all the remaining pieces into one entity. As an extremely powerful force of will, the brain is shown to be able to manipulate and hypnotise the weaker-minded and may even possess even higher functions such as mind-reading or telekinesis.
Before the course of the Grandia II story, Pope Zera is possessed by the Brain of Valmar at some point (possibly even before becoming a clergyman), which he then uses to influence and beguile countless followers into adoring him. He uses this hypnotic ability in his attempts to persuade Ryudo and company to abandon hope of stopping Valmar's revival, playing on their emotional baggage and insecurities as ammunition.
It is stated by Zera, that he wished to become the will of Valmar and shed his mortal coils only to use Valmar and become a perfect God himself.