Jesters of Armok are sapients of many kinds, be they dwarf, elf, human, or what have you, taken by Armok and given the means to entertain him. Most who do not hide this are often great monarchs and generals, or rembered for thier deeds long ago as various heros or villians. Dwarves know of the Jesters and often name thier children after them.
It is known some had at one time dragon mounts. Whether these were given by Armok for the occasion they were used or were tamed beasts of war is unknown, though it is speculated to be a mixture of the two.
Jesters are somewhat common, more comman than many believe, but many choose to go the route of closest vampires and necromancers, living a facade of a normal life unless pressed; something that happens fairly often. Jesters have an ability to "Respawn," and are locked at the time of taking. Any other abilites they have are either learned, natural abilities they had prior to being taken, or are bestowed by Armok on those he favors.
Simply the ability to come back from the dead, as it were. When a Jester dies from disease or injury, Armok prevents thier soul from passing on and fashions a new body for them in the form and image of the old. This is noted as being an unpleasant expeirience, largly because the death was probably a visceral and messy affair and because there is some residual pain from the injuries afterward (headaches for deaths caused by head trauma or limb pain and faintness if they died from losing an arm and bleeding out.)
This process is deemed a break by most Jesters, and they reside in Armoks meadhalls for as long as three weeks after, depending on how much kicking and screaming was involved in thier death; if one fought on to the end, Armok is more invclined to let thier soul rest for a longer period, as they have earned that much in his eyes. On the inverse, if they surrendered or died running, they may at best have three days before a new body is formed, thier soul jammed in like a cube ina round hole, and they are dumped somewhere near where they died, preferably in trees or face down in a stream.
Another humerous side effect is thier old bodies don't vanisj or anything similar, leading to those funny occasions where a Jester may find his own corpse while in the company of others, leading to many an awkward explanation and silence.
Like Necromancers and Vampires, Jesaters "Lock" in that they will no longer age past thier current age. For the vast majority this means they remain relativly young and physically capable, something needed for a servant of the god of war and blood. This also afford them the means to become truly formidable warriors and well learned scholars, such as Splint Leanhelped who was shown to be a much stronger foe than expected by Ballpoint's Contractors, something attributed to the centuries he's had to practice. For some racesa, such as elves and goblins, this is a somewhat moot trait however, as they are already biologically immortal.