Mace of Smiting

Melee Weapon, major, rare

• Damage: 1d6 B
• Weight: 4.0 lbs.

You gain a +1 bonus to attack and damage rolls made with this magic weapon. The bonus increases to +3 when you use the mace to attack a construct.

When you roll a 20 on an attack roll made with this weapon, the target takes an extra 7 bludgeoning damage, or an extra 14 bludgeoning damage if it’s a construct. If a construct has 25 hit points or fewer after taking this damage, it is destroyed.

Note

According to the SRD, it is an extra 2d6 and 4d6 bludgeoning damage, although this is incorrect (https://rpg.stackexchange.com/a/174522/53884).

Source: Dungeon Master’s Guide p. 179. Available in the SRD.