Source: Unearthed Arcana 83 - Giant Options

Prerequisite: 4th Level, Rune Carver Apprentice Feat

Your skill with the art of runecraft has increased.

Whenever you finish a long rest, you can now mark a number of objects equal to your proficiency bonus with a rune from the Rune Carver Apprentice feat. An object can have only one rune at a time, and you must inscribe a different rune on each object.