Mothman is a Persona of the Hermit Arcana in Persona 3 Reload, and it's also required to complete one of Elizabeth's Requests. Even if you never use Mothman for battling, this Persona can be used in various fusions to make potentially stronger Personas for the late-game phase. What makes Mothman different from most Personas is its unlock requirement. You'll need something called a Vibrant Feather to obtain Mothman's fusion recipes in Persona 3 Reload. Fortunately, this key item is guarded by one of the Gatekeepers in Tartarus, so it's impossible to miss. With it, you can fuse Mothman to complete Request 35 - Fusion Series #3: Hermit, Mothman.