Chaos Blast

From the Sonic News Network, the Sonic Wiki

Chaos Blast is a move that only Shadow the Hedgehog is known to use. This move was introduced in Shadow the Hedgehog (game), and was originally designed to be used when his heart was full of evil. However, due to modifications through several games, Shadow can now use it without commiting any acts of evil and is only required to charge enough energy, or enter his Chaos Boost form. It's appearance is literally a great shockwave of chaos energy that destroys all in its limit range. During the development of this move, Shadow's eyes and stripes begin to glow.

Shadow can also use this move in Sonic Chronicles: The Dark Brotherhood, Sonic the Hedgehog and Sonic and the Black Knight.