Dark Shadow

Dark Shadow is a state of full control over negative Chaos Energy achieved by Shadow the Hedgehog in the game Shadow the Hedgehog that allows him to become invincible and use Chaos Blast for a limited amount of time. In most cases, Dark Shadow can be obtained through committing dark actions and filling Shadow's Dark Gauge. The only other instance this form can be obtained is when fighting the Egg Dealer and causing all three Shadow Fever icons to appear on the slots. It should be noted that Dark Shadow is a different ability compared to Chaos Boost however, the two bestow Shadow with similar abilities, suggesting the two may be related.

Trivia

 * Both Dark Shadow and Chaos Boost can only be used by Shadow.
 * When facing the Egg Dealer and initiating Shadow Fever, Dr. Eggman will announce his discontent at the slots landing on Shadow Fever shouting, "N-no! Not Shadow Fever!"