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Double Impact (ダブルスライド, Daburu Suraido?, lit. "Double Slide") is a technique that appears in Kingdom Hearts 3D: Dream Drop Distance. It allows the user to perform a second charging attack after using Sonic Impact which sends enemies flying.
In Kingdom Hearts 3D: Dream Drop Distance, Double Impact is an movement command that is triggered by and pressing immediately after using Sonic Imapct.
Learning Double Impact
Kingdom Hearts 3D: Dream Drop Distance