In the Apocalypse, the System Tricks Me into Slaying Dragons

“In three years, dragons will destroy the world, blasting planets apart with a single breath! If you don't want to die, hurry up and level up!” Shen Yuan believed the System and spent years cultivating with everything he had, mastering countless dragon-slaying techniques as he waited for the final battle against the dragons. The apocalypse arrived right on schedule, but there were no dragons blotting out the sky, only a horde of slow-moving little zombies, moaning as they shambled along. Staring at the dragon-slaying blade in his hand, capable of cleaving apart the stars, Shen Yuan was completely dumbfounded. “Damn System! What happened to slaying dragons?”