So as you remember...
He arrived on the beginning of the Fan-Comic in the previous version as
Phantom Luigi.

And he's a "Decoy Fog", that can distract the Characters that are on
Dr. Golden "Preparation" side. Also, he can unload Mecha Balloon Toad
for some time, so the Toy Animatronic won't disturb Silent (The Player/Avatar).
He's summoned from the device that is called "Essence Plasma Interceptor Carrier" (Item description:
Yeah, probably don't sound very grammatical, but it's about the shortcut in
the name... E.P.I.C. !!!).

Also, after Phantasm Luigi disappear.
Silent can use the fog that he left to use hers Stealth Ability to sneak from the enemies sight and move around in safety until... the ability runs out of the timer.

Well, I think that's it.

Hope you like it.