Nie Li felt a little dizzy and his consciousness felt a little fuzzy. These were side effects from exhausting his Heavenly Energy.
It seemed that the task of forcing a fusion was still too difficult for him, especially with demon spirits of such high growth rates. After all, these processes usually had low success rates. Nie Li focused and squeezed out the last of his energy. If these two demon spirits actually exploded, then all his refining from earlier would go to waste