Dwarven Thrower

From Dungeon Master's Guide, page 167. Found on Magic Item Table H.

Description
Weapon (warhammer), major, very rare (requires attunement by a dwarf).

You gain a +3 bonus to attack and damage rolls made with this magic weapon. It has the thrown property with a normal range of 20 feet and a long range of 60 feet. When you hit with a ranged attack using this weapon, it deals an extra 1d8 damage or, if the target is a giant, 2d8 damage. Immediately after the attack, the weapon flies back to your hand.