Maul Against Water Breathing

Weapon +1 Weapon, Heavy, Two-handed Varies (this item requires attunement)

The handle of this maul seems to be made of old white oak. The head of the mace is a deep black cast iron.   Normally a +1 Maul, when in the presence of a creature that is amphibious maul vibrates softly. When used to attack an amphibious creature, the maul becomes a +3 maul and the user can reroll any damage result of a 1, but the user must take the second roll.