Standing apart from the rest of the squad, Death Jesters provide much of the Mask's heavy weapon support. In performances, their role is to play death - they perform death-defying stunts and escapologies. They are known for their morbid and wry humor, and their mocking laugh is known to signal impending death. The Death Jester's macabre uniform is crafted from the bones of the squad's previous Death Jester - and when one dies, their bones are used to craft their successor's costume.
Death Jesters seek new and inventive ways to terrorize and ultimately kill their victims. They can sometimes be heard humming softly in mid-fight, occasionally pausing to bow or give a mock applause to an enemy. Killing an enemy is not enough for a death fool. To make the war worthwhile, they must enforce murder with wry humor. Killing an officer in the crescendo of a pep talk or sending engineers into a minefield they've just finished laying are examples of this macabre sense of Humor.
The Brotherhood of Death Fools have since allied themselves with the Ynnari. They believe that creating a god of death and destroying Slaanesh through the downfall of the race that gave birth to the ancient Nemesis would be the greatest hoax of all.
Death Fools use clothing and gear that features skulls and death motifs. They wear armor armor enhanced with visual disruption and conversion field technology. Heavy specialists in the army, they wield a range of deadly weapons, from the Craftworld Eldar's conventional shuriken cannon to the specialized firepike or the morbid Shrieker Cannon. The Shrieker Cannon is the hallmark of the Death Jesters as only they make and maintain it. They're a variant of the shuriken cannon, but instead of firing a hail of projectiles, they only fire a single shot. This shot is impregnated with a virulent acid that violently dilates the victim's blood vessels and interior. This usually results in a small explosion that showers squadmates with parts of their pet.