The Flame of Judgment is a major plot element in Sonic and the Secret Rings.
When Sonic and Shahra first entered the world of the Arabian Nights, they were attacked by Erazor. When he found out that Shahra refused to gather the World Rings for him, he shot a flaming arrow at her as punishment, but Sonic jumped in front of her and took the hit instead. Erazor then uses the arrow to blackmail Sonic and Shahra into helping him gather the World Rings, promising to remove the arrow if Sonic gathered all of the seven rings for him.
Throughout the game, it is stated that the arrow has cursed Sonic, and that the flame on it is his lifeline; when the flame goes out completely, Sonic will be completely drained of his life energy and die, and only Erazor is able to remove it, as evidenced by Sonic's request to Shahra that she does so. When Erazor summons the Ifrit Golem, the flame is partially out and it is almost completely out by the time that he gathers all seven.
When the flame nears the end of its lifespan, side effects that Sonic suffer include episodes of physical weakness.
If Sonic tries to take the flame out himself or extinguish it with his hand, the curse seems to intensify, thus causing supernatural effects as shown in the opening sequence of the game (sand and wind circle Sonic in an almost destructive manner). Also, the Flame neutralizes all of Sonic's attacks against fire-based genies such as the Ifrit Golem.
Apparently, the curse is negated when Sonic is transformed into Darkspine Sonic by the World Rings, as the arrow has disappeared and no mention of it is was made again.
Noticeably, the gameplay in Sonic and the Secret Rings shows that Sonic can use the Flame of Judgement for various uses, such as projecting his flames from his body that turns from Blue to Orange when using a charge jump, using his flames for his fire step that they will project around him, in which induces torching-like noises, burning point on Soul Gauge and more. This is also seen on the images on Google that shows Sonic holding his Flame of Judgement in his palm and showing it, that he is probably able to redirect it from each part of his body because it's his lifetime and he can have full control of it to protect his from danger just like his Adrenaline in his body.
- In certain cutscenes, the Flame of Judgment is nowhere to be seen on Sonic's body.
- Apparently, the Flame of Judgment cannot be put out by water, indicated during one cutscene when Sonic was standing in the rain and the flame continued to burn.
- It may be that Sonic losing his Flame of Judgement at the ending is probably because he may still have the Flame of Judgement but dormant in his body.