The Heavenly Star Realm of the External Incarnation only requires Rank-1 malevolent energy to establish a foundation and condense acupoints.
Once completed, it will naturally absorb nature's spiritual energy and continuously enhance.
However, this enhancement is exceedingly slow; if higher-ranked malevolent energy is directly refined into the acupoints, it can shorten the time by several folds, even by a dozen times.
For this reason, this grand technique of the External Incarnation, even in ancient times, was rarely cultivated to the Perfect Realm within the Longevity Sect.
After all, Rank-2 and Rank-3 malevolent energy is still relatively easy to find, but Rank-4 and Rank-5 are essentially treasures that stabilize a sect, or even the foundational root for some Holy Lands' condensing methods, which they wouldn't trade away.
