The Grand Triumvirate is the final boss of King of Cards. He is the result of a fusion between the bodies and Essences of the three Joustus Judges merged together by the dark magic of the Enchantress.
The Grand Triumvirate is a giant golden robotic-looking figure resembling a king. He wears a huge crown and has a big beard, as well as two large blue gems sticking out from either side of his head. His hands, attached to chain-like arms, have fingers with spiked tips. Mounted on his back is a massive disk shaped like a sun with many points.
After the Grand Triumvirate's first phase is beaten, his face and body are destroyed, leaving only his hands and badly damaged head, the latter of which now features a much scarier skull-like face with bulging golden eyes and a grin of golden teeth. With the crown gone, a larger blue gem can be seen on top of the Grand Triumvirate's head.
King Knight and the Glidewing's crew attack the Tower of Fate and King Knight defeats the Enchantress. But instead of admitting defeat, the Enchantress praises King Knight for his fighting prowess and chastises the Joustus Judges for showing weakness by hiding behind King Knight. She then decides to turn the Joustus Judges (minus the Troupple King, who had sent a Troupple Acolyte in his stead) into something "more useful" and uses her magic to merge the kings' bodies and Essences, creating the Grand Triumvirate. King Knight fights the golden giant and eventually destroys him, freeing the Kings from the Enchantress's magic.
During the first part of his battle, the Grand Triumvirate mostly attacks by shooting homing fireballs and trying to crush King Knight with his hands, but will also use attacks that reference the Joustus Judges. Sometimes, he'll shoot bouncing lasers from his eyes which are identical to the lasers King Birder shoots during his battle. Occasionally, he'll shoot bubbles from his ears and summon golden Troupples which try to jump up at King Knight. And periodically, he'll slam his hands into the ground to make spiky balls rain from the sky; these spiky balls are similar to the ones King Pridemoor throws during his battle but are colored differently. As the Grand Triumvirate uses these attacks, King Knight must attack the monster by Shoulder Bashing the blue gems on either side of the Grand Triumvirate's head.
When the Grand Triumvirate tries to crush King Knight with his hands, the impact of the hands destroys a few of the tiles making up the floor. However, when the Grand Triumvirate's health is reduced to one full health bubble, he'll destroy all remaining floor tiles, forcing King Knight to use the Grand Triumvirate's hands to keep from falling for the rest of the battle, but by then that shouldn't be too much of a problem since at this point it only takes two more hits to defeat the Grand Triumvirate and advance to his second phase.
In this second phase, King Knight must once again use the Grand Triumvirate's hands as his only means of avoiding falling to his doom. The hands will float around the room on one side while the head stays in one place on the other side and fires homing fireballs at King Knight. To damage the Grand Triumvirate, King Knight must make his way to the head, use his Shoulder Bash to get himself spinning, and jump on the exposed blue gem atop the Grand Triumvirate's head. Every time the Grand Triumvirate loses two hit points, the head will move to the opposite side of the room and the hands will slowly adjust their positions. Also worth noting is that in this phase, the Grand Triumvirate only has 10 hit points as opposed to the standard 20.
Once the Grand Triumvirate's health is brought down to 4, his head will move to the center of the room and stay there for the rest of the battle, while his hands orbit around the head.
For both phases, one of the best Heirlooms to utilize throughout the battle is the Turn Coat, as King Knight can use it to negate damage from the projectiles that the Grand Triumvirate shoots at him. Using the Turn Coat is especially helpful during the second phase, as absorbing the Grand Triumvirate's projectiles with it can help prevent King Knight from falling off into the pit below. Equipping King Knight with the Rodent Regalia is also good for this purpose as it will cause King Knight to be rescued by Propeller Rats and only lose four hearts if he falls.
- It is unknown how using the Troupple Acolyte for the fusion instead of the Troupple King actually worked, considering the Enchantress's plan involved bringing the Kings together to be controlled. This was most likely because the Troupple King was too big. Likewise, it is unknown precisely how "King Birder" provided sufficient power for the fusion, although it is possible some of the Enchantress's magic remained on the Birder alongside his new voice.
- Whenever King Knight dies during the first (and only first) phase of the battle, the Grand Triumvirate will laugh at him. That makes him the only boss in Shovel Knight: Treasure Trove to react to the player's death.
- A triumvirate is a group of rulers consisting of 3 members, which reflects the Grand Triumvirate's status as an amalgamation of the 3 Kings (technically).
- The cheat code K&DMASK turns King Knight's face into the Grand Triumvirate's.