Come to the world of famine and awaken the ability to collect and synthesize. Tang Hengdao + Mantis Blade Arm = Sharp Tang Hengdao Sharp Tang Hengdao + Dragon Scale = Tang Hengdao with Dragon Power Tang Hengdao with Dragon Power + Dragon Horn = Dragon Slaying Sword?
...Synthesize wood to get a campfire. [Bonfire (green): evil fire, wood fuel, cooking] Bonfire + RV = wood fuel base vehicle.
Wood fuel base vehicle + tank = mobile base. Mobile base + helicopter (or jet) = sky fortress?
This world has experienced century-level disasters. People have been sleeping in shelters for hundreds of years and have changed beyond recognition when they come out. The world's water resources have been depleted for unknown reasons.