Pisces Shield

Alter: This round ioron shield is emblazoned with two spiraling golden koi. If the shield is submerged in water for at least 1 minute, the koi begin to animate and swim across the surface of the shield for up to 24 hours. While the koi are swimming in this way, the next time you roll a 1 on the d20 for an attack roll, ability check, or saving throw while holding the shield, you can treat the roll as if it were a 20 instead. When you do so, the koi stop swimming, and they can't swim again until 24 hours have passed.

Attunement: No
Rarity: Uncommon
Type: Shield
Cost: 345gp

Griffons Saddlebag, Vol II

more common amongst the merfolk