The first battle against King Arthur takes place on a short stretch of terrain, unlike the "circular" battlefields of the Knights of the Round Table.
At the beginning of the battle, King Arthur gallops a short distance on his horse before turning to face the player, who must then swing their sword when Deathcalibur begins to glow. After three swings, the player can jump to damage the king, who gallops away once more. The process repeats, except the second time the player chases the king, he/she is hindered by Knights of the Underworld, and the third time, the player hops on a grind rail rounding a bend. After three hits, King Arthur is defeated.
The second battle against King Arthur takes place on an endless strip of road.
When Arthur faces Sonic for the second time (this time on an endless strip of road), he has a wide variety of attacks. These include:
A magical attack originating from Deathcalibur, which shoots electricity and only paralyzes Sonic when coming into contact with.
Arthur shoots balls of dark energy at Sonic. These can be evaded by jumping over them, or striking them back with the sword. Upon doing so, the player will raise Sonic's 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 the player; this can be accompanied by the previous attack.
Occasionally, the Black Knight's arm and Deathcalibur will appear in front of Sonic from a portal. The attack is different depending on whether the player has already dealt damage to the Black Knight or not.
In order to damage King Arthur, the player must use the Soul Surge to overtake him (though using Soul Surge while in mid-air is easier and saves some energy of the Soul Guage). Once the player catches up, he/she jumps onto King Arthur's horse in front of the King and faces him. The player must swing his/her sword with precise timing when Deathcalibur's blade begins to glow. After five swings, the King leaves his chest open for Sonic to use a combo swing or a Soul Surge and damage him. Two rouds of continuous hits are sufficient to defeat King Arthur.
In the second battle at Faraway Avalon, it is possible for the player to catch up to King Arthur without using Soul Surge if using Cavalier Style, allowing Sonic to move at extremely fast speeds that will eventually allow him to reach King Arthur.
During the first fight after Arthur destroys the bridge, a rare glitch may occur where Sonic will run on the water as if the bridge is still there, instead of grinding on the rail to the side like usual.