UH OH! TRICK TIME! MWAHAHAHAHAH!!!!!
The "Phantom Illusions" from Alacrity AU specifically refer to the ones conjured in the heart of Null Space. The embodiment of one's insecurities and darkest fears.
When Sonic is sent to Null Space during the events of Forces in my rewrite, he comes face to face with two of these beings:
One is a mirror of him, except with a replica of the Phantom Ruby embedded in its chest, dark eyes, and reddish fur. Meant to represent an all-powerful version of himself who took the Ruby and used its power to play God. To prevent the world from falling apart ever again. He would be willing to take away the freedom of others for the sake of "peace".
The other is a lanky, malnourished figure, seemingly made from the bodies of his friends. It has stitch marks all over its body, many eyes and gash wounds. Out of everyone it most resembles Tails, his brother and closest friend. It's meant to represent what will happen if he doesn't accept the Ruby's power. Everyone would suffer and he would be powerless to stop it.
The goal is to distract him. To make him so mentally torn between what he should do that he never escapes. Or alternatively accepts the Ruby's power and becomes its new host. Either one works.
He's only able to escape in the end with the help of Rookie.
Thanks for playing! Tell Strawberry that Rift says hi, and Happy Halloween! 🎃