The Lightcrest is an artifact that counters the Darknull Stone and functions as its polar opposite, draining light fron its wielder and the surrounding area. Team Paradox is tasked with retrieving the Lightcrest in Paradoxical Parable II in order to stop Squidward and the Darknull Stone.
It is believed to reside in the Deep Web, a very dark and dangerous place where all light is absent. It lies beyond a desert and an ocean bisected by a massive firewall.
Because of its light draining properties, only a being of pure darkness or unlimited light can safely wield it without aid.
See Study:Light And Darkness for more information.