Only Intelligence, the others work fine... Marksmanship improves your precision, Endurance increases your life regeneration, and every point invested (not counting bonus from items) gives you +5 HP and Willpower increases mana regeneration and every point invested gives +5 Mana...
Take marksmanship through items, don't waste time on endurance, and invest equally in Intelligence and Willpower, because once they fix the bug, Intelligence will become the main stat...