Duskcrusher

A Duskcrusher is a magical warhammer with a head made of pure radiant light.

Appearance
A Duskcrusher is a leather-wrapped metal rod that bears the symbol of Pelor.

Features
While holding the rod, the wielder can use their bonus action to cause a hammer head of crackling radiance to appear, which emits bright sunlight in a 15-foot radius and dim light for an additional 15 feet. They can use another bonus action to cause the radiant head to disappear.

While the radiant head is active, the weapon has a +2 bonus to attack and damage rolls, and the weapon deals radiant damage rather than bludgeoning damage. Undead creatures take 1d8 additional damage when hit by a Duskcrusher.

While holding the Duskcrusher, the wielder can use their action to cast the spell Sunbeam, with a save DC of 15. This action can be taken once and can't be used again until the next dawn.

History
The paladin Kerrek wielded a weapon called a "Dusk Hammer" that acted similar to a Duskcrusher, having a summoned radiant hammer head that shed bright light. Kerrek used this hammer to deal the killing blow to the ancient green dragon Raishan.