Tenha Seiou Zan

Tenha Seiou Zan ("Heaven Supreme Vile Spark Slash") is one of Haohmaru's Super Special Moves, and one of his signature attacks in the Samurai Shodown series, first appearing in Samurai Shodown II.

Originally often his more stronger super in most appearances, and his Overkill in Samurai Shodown V and V Special, Neo Geo Battle Coliseum and Samurai Shodown (2019) devolved this move's rank to being a mere base super/Weapon-Flipping Technique.

Description
Haohmaru does a strong downward diagonal slash, creating a mass trail of energy in its wake. It is essentially a souped-up version of his Zantetsusen, but with notable force regardless.

While originally a meter-costing move in most games, there exist some games such as the 64 games where Haohmaru has this along with a variation just called Seiou Zan ("Vile Spark Slash") done as a followup to his Gouha series via his Bust version that Rasetsumaru does not retain.

Mysteriously, only the Neo Geo Battle Coliseum version of this attack inflicts multiple hits, while many other versions merely inflict 1 hit.

Strategy
Regardless of it being a Weapon-Flipping Technique or a powerful super in the series, it's notable due to its fast startup, range and damage.

Of course, this all mainly applies to the version that can be done on its own, whereas in V and V SP, it acts as Haoumaru's Overkill and thus has less practical applications compared to other incarnations of the move.

Interestingly, in KOF XV, the version starts 8 frames slower than the  version.

Of course, this move tends to be rather committal and is easily punishable. But on the flipside, the CvS2 version especially has full invulnerability frames at the startup along with the usual hefty range (also true for the SamSho 2019 version). This often makes it a powerful one-shot punisher at poking range for any of the non-cinematic versions.