The Great Houses face many challenges. Massive volcanoes vomit smoke and ash that blot out the sun and blanket the earth. Skaa laborers turn on their masters in riot and rebellion. Eerie mistwraiths haunt the night and rampaging koloss stalk the land, laying siege to the world of men.
In Mistborn: House War these myriad challenges are collectively known as Problems, and they appear in the Problem card deck.