The false Sephiroth was a replica of Sephiroth from Final Fantasy VII created by Francis with Inkweaver. He was also the character who killed Desti with his Masamune.
When Francis was confronted by Mario, Luigi, Tari, SMG4, Fishy Boopkins, SMG4 and Saiko, he brought to life the anime character Sephiroth and had him to fight them with him He easily defeated most of them until he saw Desti with Inkweaver he started to attack her but Saiko managed to create a distraction with the help of Tari and they attacked him until he died. But Francis got the time to bring another Sephiroth to life and the Sephiroth proceeds to kill Desti. After Sephiroth killed Desti, Francis created about 100 Sephiroths and started to attack the gang. When all hope was gone, Bob, Swagmaster69696969696 and Chris break in with a tank and kill all replicas of Sephiroth.