Grim Champion of Desolation

Grim Champion of Desolation
Jyn Corvis, a former adventurer, might have been the first person to draw the Skull card from a Deck of Many Things and be slain by the avatar of death. Even Jyn doesn't know for sure, as that was so long ago that she's forgotten almost everything about her former life. Jyn's existence over so many centuries has left her in tortured misery, and now nihilism is all that drives her. More than any other member of the Grim Harrow, Jyn is desperate to destroy the deck and end her painful existence. If she could, she'd take the entire multiverse with her.
The Grim Champion of Desolation rides a malevolent draconic beast with pale, leathery wings and emaciated skin; this mount uses the wyvern stat block, but it is an Undead instead of a Dragon. An eerie, hollow silence heralds the champion's arrival.
The Grim Champions
The Grim Harrow is led by three powerful entities with the title of grim champion. Each champion embodies a terrible facet of death. Jyn Corvis, Grim Champion of Desolation, is the oldest and most powerful of the three and embodies all-consuming nothingness. She led the Grim Harrow to the Gardens of Delight long ago and is the nominal leader of all the Undead in the demiplane. The other two champions—Wynemar Brack, Grim Champion of Bloodshed, and Aleron, Grim Champion of Pestilence—rival Jyn for power and together can oppose her. The fact that the three champions rarely agree on anything is a major check on the group's power. Instead of the Grim Harrow acting as a unified force, each of the three champions usually pursues their own interests, seldom cooperating or sharing intelligence or resources.