In this Final Smash, the Hero slashes upwards, and if the hit manages to damage at least one opponent, then they will be trapped in place, and a cutscene will play where the remaining non-playable Dragon Quest Heroes (in order of appearance, the Heroes from II, V, VI, VII, X, IX, and I) appear, and gather their weapons together, shooting energy upwards into the air, with the energy charging the playable Hero's sword, who then attacks with an outwards slash. The game cannot be paused for the duration of the move.
The Final Smash is comprised of two hits, with the second hit only being activated if the first hit manages to hit a player. The first hit of the move is a ranged sword swing with an electric effect, dealing 8% damage to any opponents that have taken damage from the hit. The second hit activates after the cutscene finishes and deals 39% damage with immense knockback. On Final Destination, the attack can KO Mario at 15% at the ledge and 40% at the center (Percentages are from damage dealt with the Smash Ball variant of the Final Smash). According to the cutscene, the second hit is presumably the result of a powerful electric slash from the sword that the Hero wields. Likewise, the second hit of Gigaslash will have an electric effect, similar to the first.
Gigaslash is a powerful, recurring ability in the Dragon Quest series, first seen in Dragon Quest V. Despite its name suggesting a physical attack, the move is a magical attack; it deals immense Zap damage on a single group of enemies. The heroes summoning lightning also resembles Kazapple, a magic spell that draws MP from the entire party to activate.