After Knuckles' death at the hands of Mammoth Mogul, his shrine was placed in Sky Sanctuary. When he returned from the afterlife during the Xorda's attack on Mobius, Constable Remington felt he was merely an impostor, and thus he and members of the Echidna Security Team went to Sky Sanctuary to examine Knuckles' shrine, at which point they discovered Knuckles' tomb was empty and realized he had in fact returned. (StH: #118, #138)
When Mobius was affected by the first Genesis Wave, Knuckles traveled to Sky Sanctuary from Angel Island through a portal in the Hidden Palace Zone. From their he could see the island and a another rather mysterious object. However, as he glided down to the island, the Gensis Wave started returning everything to normal. (FCBD: 2012)
- Sky Sanctuary Zone is based off the level of the same name in the video game Sonic & Knuckles.