Dark Shadow

Shadow Fever is a state of full control over negative Chaos Energy achieved by Shadow in Shadow The Hedgehog that allows him to become invinsible and use Chaos Blast for a limited amount of time. In most cases, Shadow Fever can be obtained through commiting dark actions and filling Shadow's darnkness meter. 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 Shadow Fever is a different ability compared to Chaos Boost but the two may be related.

Trivia

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