These blue robes with silver arcane runes stitched into the lining were created by ancient abjurationists to protect them in magical duels.

 The runes activate when the wearer is targeted by a spell that allows for a Wisdom, Constitution, or Dexterity Saving throw, allowing for a bit of better protection from their effects (+1 to saving throws).  An arcane caster can also invoke the runes to cast the shield spell once per day.  When the runes are used this way roll 1d20, on a 1 the attack overloads the runes, destroying the warding enchantment on these robes and returning them to mundane cloth.  

Notes: Bonus: Saving Throws, Bonus: Saving Throws, Bonus: Saving Throws, sorcerer, warlock, or wizard, Warding, Outerwear