Mjolnir

Mjolnir, Old Norse for "the Grinder", is best known as the personal weapon of Thor.

History
Made from Uru by the Dwarves of Nidavellir for Hela, Odin's firstborn daughter, for their conquest of the Nine Realms. Her younger brother Thor subsequently used it in his many adventures and battles.

The undisputed symbol of the God of Thunder, Mjolnir is a potent sign of its wielder's raw power and his worthiness to wield such gifts.

Description
Mjolnir is considered one of the most fearsome weapons in Norse mythology, able to raze mountains and topple giants with a single swing. In the comics, the hammer was able to be wielded by those deemed worthy by Odin's enchantment and could channel electricity through it. In the movies, it is explained that Mjolnir was merely an aid to help Thor control his powers.

Passive Abilities
Ranging Attack Bonus: You have +3 Attack Bonus and Damage Rolls while wielding Mjolnir. If your Health modifier is higher than 3, you may use that instead of +3.

God-Killer: This weapon ignores all immunities and resistances to physical and a single type of damage (Lightning)

Fortify Health: You gain 30 base health while wielding this weapon.

Magic Conduit: Magic may be cast through the artifact instead of a normal focus.

Power Resistant: The artifact is resistant to all effects and powers not cast by the wielder. This doesn't extend resistance to the wielder. It cannot be broken, transported (seperately from the wielder), or altered by an opponent if they succeed on a Proficiency save.

Whosoever Holds This: The hammer's enchantments only allows it to be picked up and or moved by those it deems worthy: those of significance to the fate of many who use it for unselfish reasons.

Energy Absorption: The artifact generates energy equal to the damage taken by the wielder. This does not negate or lessen damage, only generates energy equal to the damage taken. This may be released in any attack as Lightning, Force, or Thunder damage as a bonus action.

Active Abilities
Return: This item may be returned to the user who threw or dropped the weapon last as a bonus action from any location in any plane by the most direct path. The weapon will return to the user's hand by the user's next turn if not on the same plane. The DM may rule for damage to be taken as part of its return, for example if a creature is between the hammer and the wielder.

Torrents of Lightning: This item may be used to summon a 120 foot long, 20 foot wide arc of lightning, targeting up to 20 targets in a visible arc and dealing 5d20 damage + Character Level or Energy Absorption energy divided amongst them in lightning damage. You may do this only once per day unless recharged.

Swinging Strike: Swinging the hammer by its thong, you launch yourself towards a target that you can see, forcing them to make a 17 Dexterity save. On a fail, the target takes 6d4 Bludgeoning damage and any additional damage absorbed through Energy Absorption.

Ride the Hammer: Swinging the hammer by its thong, you launch yourself into the air, taking flight and moving at 60 feet per turn. As a bonus action, you may land either hammer first or feet first, either dealing 4d12 Bludgeoning damage to anyone in a 30 foot radius or floating to the ground.