While the Black Queen manages the affairs of ruling on Derse, the Black King leads armies in battle against the White King on the battlefield in Skaia. While Prototyped, the Black King towers over nearly all of his soldiers, standing several times the height of even the Black Rooks. Unprototyped, however, the Black King isn't too much larger than an average Pawn. This may be in reference to how in an actual game of chess, the King's playing piece is physically about 1.75 times larger than a pawn as well as being much more important, but the King's move set is almost the same (Pawn can move one space at a time in the forward direction, and the King can move one space at a time in any direction).
In a normal game session, the Black King initiates The Reckoning, causing meteors to rain down on Skaia and beginning the final 24 hours of the game during which the players must defeat him and the Black Queen. are awarded for taking down the King, although it is unknown what specifically this consists of.
Karkat explains to John that the trolls had to fight a Black King with twelve monstrous prototypings that they barely managed to kill in time.
All the troll players participated in the battle, but most important of the twelve were Aradia, whose multiple duplicates from various failed timelines repressed the psychic abilities he obtained from the Gl'Ggolyb's prototyping and turned the meteors from the Reckoning into weapons against him; Gamzee, whose Bard of Rage powers surfaced for the first time unexpectedly in this battle, dealing more damage than any of their other attacks (with the possible exception of Vriska's); and Vriska, who rolled the highest possible roll available to the Fluorite Octet, dealing the final blow. The king's scepter was thus destroyed.
Music and Fan Animation
In the kids' session, the Black King had to deal with a rebellion of the pawns led by the Warweary Villein. However, he was quickly slain by Jack Noir. Jack, with the augmented powers of the Black Queen's ring, flew down and cleaved his scepter in two, removing the King's prototypings, then decapitated him with ease.