Ruber's Black Horse is the steed, besides the Griffin itself, that it is used by Ruber, on purpose to lurk into the main court of Camelot and then to break his way into the main castle, where he would rematch with King Arthur. The Black Horse of Ruber plays a minor role in the villains wars context.
Disney Vs Non-Disney Villains War
Before the siege of Paris, Ruber guides his allies on a sneak attack on the capital of France, while he would guise his actions, impresonating as a poor man, riding on his black horse. When they pass over the gates of Paris, Ruber reveals himself and orders his allies to attack. While Rasputin drives out of the city most of Frollo's army, the leader himself retreats back to the cathedral of Notre-Dame, followed by Ruber, who makes his way to the cathedral's opening with his horse. Though, the Black Horse does not appear in the final confrontation, between Frollo and Ruber, the evil knight manage to usurp Frollo and topple him from the roof of the cathedral to his demise. The whereabouts of the Black Horse are currently unknown.
Non-Disney Villains Tournament
Ruber, allied with Eris and the Ice Nation's allies, makes his invasion on Egypt, by confronting the ruler of the dynasty, Pharaoh Rameses. He rides on the Black Horse, as the two of them battle on their steeds. Rameses brutal assault proves worse for the knight, as the Pharaoh manages to drop Ruber from his ride. The Black Horse is not seen again for the rest of the war.