Willpower defines your character's ability to concentrate. It increases your Mana, Stamina and Psi capacity, and your chance to resist mental and spell attacks.
Gains per point:
Maximum Mana: 5.00 Max Stamina: 2.50 Maximum Psi: 1.00 (*) Mindpower: .70 Mental save: .35 Spell save: .35 Accuracy: .35 (only when using Psi combat)
(*) Or more, with various Solipsist talents in effect.
Willpower modifies many talents' effectiveness.