“ 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...”
“ Most large mammals, such as elephants, rhinos, and their modern ilk are ill-suited for domestication, but that doesnt exclude their use as engines of war. Rather than raise and train the Mammoth from birth, Mammoth Handlers instead capture the wild Mammoths at a young to juvenile age and train them for war. These animals are draped in armor and are unleashed as living war machines against the foes of the Mammoth Tribe.”
“ Held in a lead sheath the blade of this sword is tipped with uranium and any wound from it, even a tiny one, will go cancerous, although the effects may not show up for months or even years.”