A wretched entity of the frozen lands, the WinterKill is the remnant of a mortal left to die in despair and endless cold.
There are many dangers at the poles and in the icy mountians of the world, but few dangers are harder to survive then an attack from an Ice Ghoul, a shadow-spirit whose very touch can be deadly.
The player characters, experienced and somewhat well known, hear rumors and travelers' tales about a distant area being overrun by dragons (or other terrifying monstrosities). The locals have sent them a message, begging for heroic aid.
When they investigate, they discover that nothing of the sort is going on. It turns out that a group of thieves wanted them out of the way so that they could rob them (or someone who would normally receive their protection).