Kings of the Hexlands
NPCs gain experience by virtue of going through their daily lives, although the rate is much reduced compared to what is gained by a life of adventuring. On the first of each month, each adult NPC gains experience equal to 1/10 of what it would take to go from the level of the hex they live in to the next level (so citizens of Aldwind, a level 1 hex, for example, gain 130 XP per month. People living in a level 10 hex would gain 2100 XP a month. This shows the ruggedness NPCs have to develop just to survive in their home hex.) NPCs, however, still follow normal multiclassing rules.