“ The peasants of the wood use crudely carved symbols to ward off wolves. They think the symbols are emblems of purity and goodness and that keeps the wolves away. The symbols work, but not for the reasons the peasants believe...
The symbols are actually arcance evil symbols which the wolves know and fear, but to which the peasants are oblivious. So how gullible are the peasants going to be when a strange horned man displaying the symbols on his shield turns up and asks for their allegiance?”
“ With a huge number of sacrificial victims, another realm long ago secretly bound a Prince of the land spirits, Iorstonn by name, thus ensuring the fertility, and improving the magical defences, of their realm. But binding that Prince to one spot has disrupted the weather and magical patterns (ley lines?) over half the continent. Things have become bad enough that a coalition has been formed to rectify the situation, once divinations have established the cause.
Your party is one of the teams assembled to do the rectification: find the binding object and steal it ('so that we can destroy it here in our realm, of course'...*) or destroy it over there. Presumably the Prince will be grateful to his rescuers and angry at the binders, but with a greater spirit like Iorstonn one can never be sure: such beings are 'tricksy'.
* Of course, the rulers of our realm might want to control Iorstonn for their own ends...”