Flaming Fortress
To think the Earth sword that he got wayyyyyyyy back then would still be important right now. Well a dragon is still a snake (Eastern ones are snakes while Western ones are lizards).
Wayyy back? Pfff. Its probably not even a decade. Don't forget, that this "Combination Divine Skill, Coffins and corpses etc.." was activated countless years ago... *cough* 100 million years ago *cough*. The Abyss obviously found the secret method (Heaven and Earth sword) wayyyy back and through some shits it lost it. That explains how the Earth sword was in Shifu's Dad's sect then passed down to MC.