Acherus Deathcharger (ability)

Acherus Deathcharger is a death knight ability that allows the death knight to summon a deathcharger mount. Every death knight will earn this ability after completing the quest Into the Realm of Shadows.

The Deathcharger is an mount.

Background
In life, this deathcharger was a horse owned by the Scarlet Crusade, and kept at the Havenshire Stables under the watch of Stable Master Kitrik. The horse was then stolen by an initiate Death knight of Acherus and returned to Salanar the Horseman, who then sent the animal to the Realm of Shadows, where one of his Dark Riders of Acherus awaited it.

The Dark Rider slew the horse and then raised it as a deathcharger. The death knight was then sent into the realm by Salanar to challenge the dark rider. If successful in killing the dark rider (most are not), the deathcharger permits the death knight to ride it. Returned to the world of the living, Salanar presents the deathcharger as the death knight's new, personal mount.

Mount Journal
''Some horses merely adopt the dark. This horse was born in it, molded by it.''

Trivia
The Mount Journal entry is a reference to a quote spoken by to  in the movie : "You think darkness is your ally? You merely adopted the dark. I was born in it, molded by it. I didn't see the light until I was already a man, and by then it was nothing to me but blinding."