“ 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...”
“ The heroes are travelling the great seas by ship. One night when the seas are calm and everything seems fine their vessel is eaten by a great whale. The end? No. They wake in the belly of the animal, it is like a great cave. Full of wrecked ships and strange things to be discovered. Will they make it out alive?”
“ A PC Conjurer or summoner, basically any mage whose sole purpose in life is summoning creatures to aid in battles and various situations, is cursed with a hex, and needs to find a way to undo the curse...before he goes mad, or his fellow PCs throw him out of the party, or worse.
Everything he/she summons, never goes away. So you'll have to figure out what the heck to do with that dire bear or fire elemental once it's done fighting the orcs for you. Eventually a caravan of bizarre creatures either annoyingly ends up following the summoner around, or they go off to cause mayhem elsewhere. Bad news for the poor spell-caster regardless.”