This magic item for GURPS is based on a magic item from Tales of the Dying Earth.
Also known as Laccodel's True Rune, this item is a copper bracelet of apparently middling value ($20). It weighs 1 lb., and is decorated with a stylized L.
The wearer is given Immunity to Magic while wearing it - no spells cast by another caster will affect the wearer. However, the wearer can use magic normally, including casting spells on himself or herself. In addition, the wearer can attempt to dispel magic by touch; treat this as Dispel Magic-25, FP cost 0.
Lesser versions exist as well:
Lesser Laccodel's Runes
Not the true Laccodel's Rune, but one of a number of copies. Takes the form of a copper bracelet of apparently middling value ($20), weighs 1 lb., decorated with a stylized L.
Laccodel's Lesser Rune: Gives the wearer Improved Magic Resistance 5 and casts Dispel Magic-15 on touch (by the rune or the hand wearing it) for a cost of 2 FP from the wearer.
Laccodel's Greater Rune: As above, but Improved Magic Resistance 10 and casts Dispel Magic-20.
Thanks for the inspiration, Mr. Vance.