If Youki were in the next fighting game (let's assume another SWR expansion) Weather condition - Netherworld Light
Effect: Melee attacks are the only ones that work (like Spring Haze in reverse) Youki runs faster than anybody else and has a crazy melee moveset. He also uses a lot of the same spells as Youmu, only stronger.
Final spell: Death Sign - The Line Between Life and Death One single sword slash. If it hits, the opponent is KO'd, end of story. It would also change the music if used in the third round like Fantasy Heaven.