Improved invisibility is the same as invisibility except that the spell stays active even after combat. Only mages who study as Illusionists learn this spell.
Who gets itInvoker · 4Eldritch · 5Enchanter · 5Illusionist · 5Mage · 5Mentalist · 5Runesmith · 5Shadow Mage · 5Transmuter · 5Warlock · 5Witch · 5Wu Jen · 5Necromancer · 6Assassin · 9Shadow Knight · 14Bladesinger · 48
See also—
Same helpImproved InvisibilityThe game uses one help file for these.