After An Lin had defeated Immortal King Feng Wuya on the Divine Source Continent, he had discovered something very interesting when searching for spoils of war within the Immortal King Palace.
Luo Yan had told him that the Immortal King had been collecting a type of crystal ore known as Dark Crystals.
Dark Crystals contained extremely rich dark-type power and could help one observe the dao and intent realm of yin or be used to unleash yin-type energy as a disposable weapon.
In short, these were dark-type energy bombs!
Luo Yan had told him that just one Dark Crystal was capable of severely wounding or even killing a top-rate exalted immortal.