||You shall regret the day you ever raised your sword against me!
— King Arthur
The fight against King Arthur on Faraway Avalon is the second and final time Sonic faces the fallen monarch in Sonic and the Black Knight. After gathering the Grand Kingdom's Sacred Swords from the Knights of the Round Table, and proving himself chivalrous enough to receive Nimue's secrets, Sonic heads to the Black Knight's island fortress of Faraway Avalon for a final showdown.
As in their previous fight at Misty Lake, this boss takes the form of a running battle, as the black knight rides his horse away from Sonic, periodically conjuring up unpleasant magical attacks with Deathcalibur to impede the hero's pursuit. These include:
- A magical attack originating from Deathcalibur, which shoots electricity and temporarily paralyzes Sonic.
- Arthur shoots balls of red-black energy at Sonic. These can only be evaded by bouncing them back with Caliburn. This will raise the soul gauge.
- His most powerful attack, but the easiest one to avoid, is when the player lags behind him. He turns around and charges his horse at you, scattering red/black spheres in his wake. This attack can be most easily avoided by simply holding .
- Occasionally the Black Knight's arm and Deathcalibur will appear in front of Sonic from a portal. The attack becomes more destructive if the Black Knight's health is low.
After being thrown off his horse, the boss simply laughs at Sonic; with the Scabbard of Excalibur still in his possession, Arthur is entirely indestructible... except for the magical trick Nimue has taught Sonic. Triangulating the king between Lacelot's Arondight, Gawain's Galatine, and Percival's Lavaetin, the hedgehog strikes a coup de gras with Caliburn and finally destroys Arthur. The monarch's corpse, however, proves the most intriguing part of the battle, in that it dissolves into black mist, just like the Knights of the Underworld. It seems that someone has some explaining to do...