Corrupted Ashbringer

Corrupted Ashbringer is a Legendary Two-handed Sword in Diablo III, added in patch 2.2.0. It requires character level 70 to drop.

The unique affix skeleton raise has no internal cooldown and a relatively low chance (and, obviously, is useless against bosses that don't summon minions), but these skeletons do not have timed life, are invulnerable, and deal roughly 100% damage as Physical. They move quite slowly, however, so a fast-moving character may leave them behind easily. The empowered sword lasts approximately 10 seconds, and adds extra damage to every attack, regardless of its Proc Coefficient. Exploding skeletons have very small radius (10 yards at most), but their blasts may overlap, potentially dealing full 5000% damage to a single foe.

The extra damage will not trigger on Damage Over Time attacks (Rend, Locust Swarm, Haunt, Firebats, Piranhado, Energy Twister, etc). For other skills, it happens one time per cast, usually damaging the first enemy hit, or the one closest to the center of area of effect. Proc Coefficient is ignored for this purpose.

It is also one of the few items with bonus damage against undead.

The Corrupted Ashbringer is one of the rarest items in the entirety of the game for balancing reasons (both normal drop rate and even success rate of transmuting it using Kanai's Cube). Also, its Legendary affix may not be extracted via Archive of Tal Rasha transmutation.

Trivia

 * This sword is taken from the Warcraft universe, under the exact same name: Ashbringer. If one listens in-game and in the character screen, they can hear faint whispers, similar to the World of Warcraft item.
 * The floating skull always gazes at the player, regardless of the sword's angle to the camera.