Perhaps you can help by uploading a picture of animations of Sonic Impact being use in-game.
Sonic Impact (ソニックスライド Sonikku Suraido?, lit. "Sonic Slide") is a technique in Kingdom Hearts Birth by Sleep and Kingdom Hearts Birth by Sleep Final Mix. It allows the user to chain multiple Slide techniques by allowing him to perform an extra charging attack.
In Kingdom Hearts Birth by Sleep, Sonic Impact is a Movement Command that has a maximum level of 4 and fills the Command Gauge by 20% for each time it hits an enemy. It is availible only to Terra, and can be linked off of Slide or Air Slide by pressing Square while using either technique. The move will usually cause an enemy to stagger when it hits them, interrupting their actions. Unlike Slide, Sonic Impact carries no invincibility frames with it, so using it is risky. Even if Sonic Impact is equipped, Terra can still repeatedly Slide to defend himself if the player properly times his inputs so as not to activate Sonic Impact.
Learning Sonic Impact
- Terra-Xehanort inherits Sonic Impact from Terra. However, his version of the attack is charged with the power of darkness. When Terra-Xehanort uses Sonic Impact, he does have invincibility for the attack, allowing him to evade attacks and attack the player at the same time. As such, he will use the attack to evade any high-power Magic commands used by the player, which makes Aqua's fight with him very difficult.
- No Heart can also use a variation of Sonic Impact in his battle.