Memory of the Beyond

You can tap into your fleeting vision of the unknown to imitate unnatural creatures with perfect clarity. As an action, you can expend a Bardic Inspiration die instead of expending a spell slot to cast polymorph. When you cast the spell with this feature, you assume the form of an aberration or monstrosity instead of a beast. The aberration or monstrosity must have a challenge rating less than or equal to one-third your bard level. While the spell lasts, you can roll the Bardic Inspiration die after you hit with a weapon attack and add the result to the damage. This bonus damage can only be applied to one attack per use of this feature.