Winter-Beast

From the introduction:

Pendor is the northern-most town in the kingdom of Elb. It lies very near a particularly dangerous part of the Northern Mountains, however, it is protected by the Pendor River. The river is shallow, but swift and wide. No bridges cross it. The river keeps creatures from the mountains away from Pendor. In the Winter, the river freezes solid, allowing wild creatures from the mountains to cross into town. Many people retreat to the south for the summer, and hire brave, adventurer types to guard their property.