D&D 5E: The Dryad's Dragon - Setting Quirks

Stone and Salt and Steel: Stone, Salt, and Steel in sufficient quantities grant characters Advantage against undead creatures. If a character has stone underfoot (may not be covered by more than a half inch of other material) or is wearing steel armor (steel weapons alone are not enough to grant advantage) have advantage on all actions against undead, including saves.

Characters who spend an action encircling themselves OR an undead creature with an unbroken line of salt (or who are standing in salt water) have advantage on all actions against undead, including saves.

Undead cannot cross salt lines or exposed stone without taking damage (1d6/rd).

Name of the Made: Characters who hold an inscribed copy of a magical construct's name (such as a golem or simulacrum) have advantage on all actions against that creature, including saves.