Lin Dong knew that there are only two methods to acquire more energy. This being Elixirs and Yuan Power. He deduces that the Stone Talisman isn't that interested in elixirs as it refines them. Therefor it has to be Yuan Power. Lin Dong tries to summon as much Yuan Power he can to feed the Stone Talisman. It is however not easy as he hasn't have complet mastery over his Yuan Power.