In a nearby town villagers tell tales of adventurers being driven mad by an unknown force within the woods…
When a local farmer discovers something at the bottom of his new well, the fate of the land will hang in the balance.
During their travels through a dense wooded area the high pitched sound of a scream tears through the peacefulness of the forest.
This mountain chain was once vast and impenetrable, but had the misfortune to named in the binding spell of a mighty demonic(godly?) being, namely that when the Great Mountains are forgotten, then shall it be free.
Herbalist in the group mistakes one plant for another and mistakenly poisons the group. Not to death, but pretty darn ill with recurring symptoms until the cause and cure are realized. (Local people may be able to help rather easily. "You ate Dragon's Rot you fool, looks and smells just like mint except it has these small thistles on the root. Only grow in the Hornwood Forest, that must be where ya got them. Eat this and you will feel better in 4 hours."