Even as humans can be, the Kel'Regar, too, can be touched by madness, and it can drive them to push to ends incomprehensible by the sane. The work of one such, Kararemi'ar'Salm'Torat, the Menangerie of Mad Creation, is a twisted, living structure, tormented by years of loneliness and incomprehensible need.
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.