Each character starts out at level one, requiring experience attained through successful combat to increase. Character levels determine the amount of power they have during combat calculations, and in turn determine the SKILL payout on victories.
Level milestones are specific points where the character receives a large boost in power, and in turn increases their SKILL payout.
Currently, milestones occur every ten levels, starting from 11 then 21, 31, 41, etc.