Every adventure, roll a CON check with a -4 bonus. If you fail it, you've failed to create arrows. If you make it, you've created 12 arrows.
Other arrows that can be created and bonus/penalty to check, and the cost of maerials, fall or succeed:
-- Fire arrows; does an extra 1hp damage for flame, -2 to hit, can start fires (-2 bonus; creates 12; costs 5cp for materials)
-- Signal arrows (+0 bonus; creates 12 Shrill, Bird Cry, or Moan Arrows; costs 10cp for materials)
-- +1 arrows (+2 penalty; creates 6; costs 25cp for materials, requires a mage of any level or arcane wood, as from an elven or druidic grove)
-- Ojibwe clan arrows (+4 penalty; creates 4; costs 50cp for materials, requires a mage LV 6 or higher or a cleric of LV 6 or higher, from the appropriate clan)
-- Soul-Claimer arrows (+8 penalty; creates 2; costs 150cp for materials, requires a mage of LV 10 or higher) - 20 sucks up enemy soul; 18 or 19 absolutely stuns them for 1-4 rounds (i.e. they can be dispatched by a throat-cut, etc.)