The new challenge league features cracks in the earth that spawn vicious monsters. Pursuing those cracks to their sources leads to the rifts that are spawning these monsters down below; if you’re very lucky, you might even get a chance to travel into the Abyssal Depths. There are new Abyss Jewels and Abyss Armor to go along with these new challenges, so players will have every reason to head into the dark places where light has no purchase. Because, really, you’ll get new stuff. Isn’t that the point?
Source: Official Site