Boundary Stone
Two stones in a line, at one height and no farther than sixteen blocks apart, stretch a boundary between them: monsters and automatons cannot cross it, people and animals walk through.
kindblockcreative tabFluxiongroupArtifice
Currents
Ward3
Strata2What the Loupe reads: 5 in all. Wheel of Currents
In the Codex
Entry 
Towpath and Boundary — A road that carries you itself, and a boundary no monster crosses.
Device
Device group: Artifice.
