Lachdanan (Quest)

Lachdanan is a quest that takes place on level fourteen of the dungeon in the original Diablo, and begins when the player speaks to the Unique Blood Knight of the same name.

He informs the player that he was once one of King Leoric's Royal Guard, but as Diablo corrupted the King, he cursed the knights who were not there to protect him to serve the Lord of Terror in darkness for eternity. All the Royal Guard turned into evil mockeries of their former selves, save one: Lachdanan, who, upon discovering that the others of his order had been corrupted by Diablo, was forced to defend himself against them, and ultimately slew Leoric, who cursed him to eternal damnation with his dying breath.

Lachdanan then tells the player of an elixir that could free him from the mad king's curse, located on the fifteenth level of the dungeon (random spot on the floor). Upon returning the elixir to Lachdanan, he thanks the player, who then receives the, a Unique Full Helm, as Lachdanan disappears.

Diablo III
This quest returns in The Darkening of Tristram event as a corpse curio. The player will find Lachdanan's corpse in Labyrinth Level 14, and upon accessing it will spill items, gold, and a version of the Veil of Steel helm.