Pages 33, 40, 77, 83, Missing Naffatun rules
Naffatun: Specified units may be upgraded to include naffatun incendiary projectiles. Naffatun is “fired” in the same manner and range as javelins. Two dice per unit are rolled separately for missile fire, replacing the regular missile weapon (e.g. if a unit of 12 archers fire, 10 dice are rolled for bows and, assuming they are in range, 2 for naffatun). If these hit they ignore enemy armour - no armour tests are allowed and 3+ is required to kill. Any unit hit by the fire must test morale as if it had taken 25%+ casualties from missile fire.
Edit: Stu's checked this, made a minor amendment and so it is the official rule