A Fluctuator is gadget that allows an elf to modify the density of an object.
“They must've had a Fluctuator alter the stones' density. You'll understand once you feel them.”
—Mr. Forkle, in Lodestar
The Neverseen used a Fluctuator, which Mr. Forkle deduced when they visited a hideout in Lodestar. The entrance to the hideout used rocks with altered density, allowing elves to pass through them. In Nightfall a fluctuator may of been used in Quinlin and Livvy's apartment to lead to a secret library. As of Unlocked it is determined to be a gadget, as it is not listed among the official abilities.