- You may be looking for Angel Island from the Prime Zone, Angel Island (Light Mobius) from Light Mobius, Onyx Island from Silver's Future, or Demon Island from Moebius.
Angel Island was a floating island in the Another Time, Another Place Zone and home to Knuckles the Echidna. Knuckles and Tails used the only remaining Chaos Emerald and pieces of Tails' Tornado plane to build a trap for the Marauders, a group who had stolen the other Emeralds. This resulted in a brief battle between Knuckles and the Marauders, ending in his defeat at the hands of their leader. Tails then left to get help for the captured Echidna, hoping to find Sonic the Hedgehog. (StH: #191)