Glancing blow

Mario's forward tilt barely touches Wario, resulting in a glancing blow.

A glancing blow, originally known as a phantom hit, is the result of a hitbox making tangential contact with another fighter. It originated in Super Smash Bros. Melee and returned in Super Smash Bros. Brawl.

Glancing blows occur when an attack only just hits a target, and are usually accidental. In terms of the game's physics, the edges of the attack's collision bubble and the target's collision bubble are tangential (overlapping on only one point), as opposed to a normal hit, in which the collision bubbles overlap. Any attack has the potential to be a glancing blow.

Glancing Blow in Melee. This animation demonstration four different occurrences involving Glancing Blow.

In Melee, glancing blows were commonly called "phantom hits", as they weren't given an official name until Brawl. Such hits would do half damage with no knockback, but there is nothing indicating that a glancing blow was made.

In Brawl, glancing blows make a very quiet "chik" sound and produce small orange sparks; the attack doesn't deal hitstun, damage, or knockback to the opponent. Glancing blows do not count as a hit and can become normal hits if the hitbox proceeds to make a solid connection afterwards (for example, advancing projectiles may deal a glancing blow on one frame and then connect on the next).

Glancing blows are rare and difficult to intentionally achieve, simply because the required circumstances (tangential collision bubbles) are correspondingly rare. As such, they are generally seen as an accident. However, some characters are set up for a glancing blow when in the Online Practice Stage; Jigglypuff starts exactly the right distance away from the Sandbag to achieve a glancing blow with the first hit of its standard attack (jab) or the third "hit" of Sing; and one of Kirby's down tilts will put him exactly the right distance away from the Sandbag so that a repeat will result in a glancing blow.