Sword Seal

*As a disciple of a small clan had chanced upon a broken sword.  
Who would knew this sword is called Skydark, and it gave him the strongest cultivation technique —— [Heaven's Underworld].  
Could he seize this opportunity to shock the world？ 
Could he take the heaven's heritage and exterminate the unrivalled enemies？ 
After disrupting the wind and cloud, and exterminate the evil spirits outside this region, Could he creating a brand-new world？