“ Unbeknownest to the character, he is in the royal bllodline. Suddenly the majority of royals fall ill and die, and the hero is left with the crown, but no experience or idea of what to do.”
“ While travelling near the edge of a forest the air is filled with the wailing of battle horns. Soon a large group of mounted cavalry will gallop by in a panicked rush. Some will spot the party and shout 'Flee! Flee for your very lives!'
Several minutes later, hundreds of running infantrymen will be spotted. A large group of white clad knights fiercely chanting a battle song is in full pursuit. One of the white knights carries a banner of a white horse on a black background. The horse is rearing under a gold crown, indicating the presence of the Paladin Prince. As the horrified infantrymen struggle to flee into the forest, the zealots charge into their midst and cut them down by the tens and hundreds.”
“ 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...”