This powerful artifact was made to combat undead.  Any undead that touches it, or any evil creature that tries to attune to it, takes 8d8 radiant damage.  While using this weapon, you get a +3 bonus to attack and damage rolls.  In addition, the weapon deals an extra 1d8 radiant damage, or 3d8 radiant damage to undead.  When you kill an undead with this blade, it explodes in a 30-foot radius sphere.  Any undead within range must make a Wisdom saving throw.  On a failure, they take 3d8 radiant damage and are frightened of you.  Creatures immune to Turn Undead cannot be frightened this way.  On a success, they take half damage and aren't frightened.  As an action, you can create an explosion of holy light.  Each creature you choose in a 30-foot radius sphere centered on you must make a Constitution saving throw.  On a failure, they take 8d8 radiant damage and are blinded until the end of your next turn.  On a success, they take half damage and aren't blinded.  Undead targets fail automatically and take maximum damage.  Once used, this ability can't be used again until the next dawn.  While attuned to this weapon, you are permanently under the effects of a protection from evil and good spell.

Dawnbreaker is a lawful good sentient weapon with an Intelligence of 13, Wisdom of 18, and Charisma of 16.  Its sole motivation is to destroy every single undead in the multiverse.

This artifact can only be destroyed by a CE lich casting disintegrate on it each day for 1 year.  Even then, it reforms in 1d100 years.

Proficiency with a longsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Damage: Slashing, Damage: Radiant, Damage: Radiant, Frightened, Blinded, This is based on the daedric artifact from TES V: Skyrim. The original enchantment reads: Burns for 10-15 points, and if killing undead has a chance to cause a firey (actual spelling in-game) explosion that turns or destroys nearby undead., A good-aligned cleric or paladin, must be attuned to in a place where you can see the sun, Damage, Debuff, Combat, Bane, Sentient, Versatile