Lex took more time to familiarize himself with the necklace, as well as his surroundings. Although the necklace had the potential to allow him to display its full power, it could not absorb and emit energy at the same time - something Lex learned after a little experimentation.
That meant his dreams of being all powerful were quashed. At least the toughness of the necklace matched that of his true body, meaning that it would not be so easily destroyed.
Lex estimated that currently the necklace had the same amount of energy as an average level 3 Qi training cultivator which was… far from sufficient for his means.
If he focused, he could accelerate the rate at which the necklace absorbed energy, but he would ultimately be limited by the ambient energy. The best case scenario would be to find a region within this land with more abundant energy, and absorb from it there.
