Of course, although Sword Spirit Transformation into Void could let a damaged Immortal Sword recover, the number of times it could be used was not without limit. Everything had its measure, and Sword Spirit Transformation into Void was no exception.
It was said that there were two conditions for performing this technique.
The first was that a treasure called Outer-Domain Heavenly Gold had to be added to the Immortal Sword.
Outer-Domain Heavenly Gold—one could tell from the name alone that it was no object of the Spirit World. In fact, even if one looked across the Ancient Demon Realm and the Underworld Realm, it was likewise nowhere to be found.
There was only one source from which this treasure could be obtained!
Slaying an Outer-Domain Heavenly Demon that had crossed realms to arrive.
Take note: an Outer-Domain Heavenly Demon, not the Heavenly Demon Lin Xuan had encountered back in the Ice Sea Realm.
The two differed by only a single word, yet they were as far apart as heaven and earth.
To make a simple comparison, the gap between them was just like that between an ordinary Ancient Demon and an existence at the Saint Ancestor level.
Back then, by lucky coincidence, and only after exhausting every hardship, Lin Xuan had managed to kill an Outer-Domain Heavenly Demon. But that had also been because his luck was not bad. If what he had encountered had been a Heavenly Demon, forget crossing hands against it—if the other party had so much as twitched a little finger, Lin Xuan would probably have had his soul return to the underworld.
These words sounded somewhat exaggerated.
But they were absolutely, extraordinarily true, and were not alarmist in the slightest.
An Outer-Domain Heavenly Demon—how could that be something easy to slay?
As for where they