New book, new battles. Last season, The 100 ended with a series-altering finale that marked the end of "Book One" and set the stage for a whole new world in Season 6... literally. With Earth fully uninhabitable thanks to the general terribleness of humanity (and a few real poor choices from Clarke and Co. along the way,) our survivors are landing on a new planet, but it looks like the gorgeous and inviting land known as "Sanctum" might not be all it's cracked up to be. After all, it wouldn't be The 100 if there wasn't …