When performed, Marth holds his sword in the air and then rushes forward at an extremely fast speed. If Marth makes contact with an opponent, he will stop and deliver a powerful, reverse-gripped slash that deals 60% damage and very high knockback, which is often enough to be a one-hit KO. Upon hitting, a gauge will appear below the opponent that starts full at 80 and reduces to 0. However, if Marth misses the strike, he will continue to rush forward until he hits something, or by a press of the special attack button, where he ceases the attack. He rushes forward for a total of one second, and unless there is something in his way, he will often go all the way to the blast line and KO himself, making it a risky move to perform.
The critical hit is a staple feature of many role-playing video games, often being an attack that has a certain ratio of occurrence and deals at least double the current damage done normally. In the case of the Fire Emblem series, critical hits inflict three times the standard damage if performed, accompanied by a unique attack animation. Because it is usually much more than enough to kill an enemy in a single hit, the damage output and particularly the knockback of the Final Smash are extremely high to reflect this. The animation is loosely based on Marth's Critical Hit animation from the first Fire Emblem game, where he was first introduced.
The gauge that appears represents the Hit Point (HP) system used in the series. Its design in SSF2 is similar to its design in Fire Emblem: Shadow Dragon, a remake of the first FE game. Oddly, the gauge in SSF2 has 80 units of HP, whereas the maximum HP in Shadow Dragon in 60 units, and the HP itself depletes from the bottom gauge first in SSF2, rather than the top gauge like in Shadow Dragon.