Prismatic Gown

While it always remains perfectly fitted to the wearer, this ballroom gown constantly shifts between thousands of colors, styles, cuts and patterns. While wearing the _prismatic gown_, you gain _advantage_ on _saving throws_ made for the effects of spells from the prismatic school due to the odd magic woven into it.

Source: Level Up Advanced 5e · OGL-1.0a · 5.1