The Court of Five Shadows was the ruling body consisting of the Dukes, who ruled the land with iron fists/claws/other appendages and supposedly basked in the infernal light of the Overlord’s hellish glory. "But what about me?" groused Grundar, the sixth Duke. "I'm a Duke too! Why isn’t it the Court of Six Shadows?" To which the Overlord merely gave the tiniest of smirks and the other Dukes gave each other clandestine high-fives.
Grundar came late to the party, serving as Duke for a mere five years before the Overlord’s fall, and many have blamed him for instigating the Overlord’s one-way trip into the volcano. In truth all the Dukes had a hand in the assassination, since the job required their combined efforts and they all concluded (correctly) that if the attempt failed, the Overlord would punish them all equally regardless of whether or not they had participated. (The Overlord’s wrath was mighty but not very precise.) Nonetheless there’s little doubt that Grundar’s incessant complaining pushed things along.
A mighty warrior and capable sorcerer, Grundar goes through a lot of seconds-in-command, since the Duke tends to react poorly to the smallest perceived insult or hesitation to follow his orders. Since he is known to wantonly slaughter his own officers, they are naturally hesitant in his presence, which sort of exacerbates the whole problem.