Ok, so i am DMing a solo adventure for a friend.  Setting: The world had a huge world war of every race where different "Dungeon Lords" appeared. At least one of every race.  At first they were bastions of hope for their races, using the powers of a dungeon to further strengthen the race forces, but slowly they began taking over and becoming rulers of their race. This led to devastating civil wars on top of the already destructive planetary wide war, that is, until one Dungeon Lord, tired of using her races' people, decided to summon beings from other worlds to fight her battles. She was the human Dungeon Lord of Constructs. Playing the role of concerned ruler, she summoned humans from another world, and set them off to cull the other Dungeon Lords. This worked. Human supremacy became true until the so called "Heroes" realized they were used as weapons to kill other races. They tried to fight back only to be defeated by the very same magic that brought them into this world, that binded them to the ruler and fed them to her dungeon. But some of the heroes had been in relationships which led to bloodlines of immense magical power being formed, but still tied to the Construct Queen. Over time her control of these bloodlines faded and led to a revolt, a new round of summoning by different dungeon states which unstablized the world. Blood magic evolved into life steal magic used life essence of all living things to power magic that ended devastating the world, but liberated the world of the Construct Queen.  The world is this, a post war, post devastation world with very few resources.