Mordenkainen's Lost Notebook

Prismatic Bow

8-level Evocation

You cause a glittering longbow, containing every hue of the rainbow, to appear in your hands. You are proficient with this magic weapon, which functions as a +1 longbow. In addition, once per round, you can use an action to imbue an arrow with one of the seven colors of the bow, chosen from the list of colors created by the prismatic spray spell, and fire it at a target within range. In addition to its normal damage, on a hit, the target must make a Constitution saving throw or suffer the same effect as the prismatic color of the imbued arrow. Once you fire an imbued arrow, that color disappears from the bow, and you can’t select that color again. When the duration ends, when you have used the effects of all seven colors, or if you drop it, the bow vanishes.