A fifth enemy called Melusine with the same sprite appears in the game's data, but is a dummied enemy. She would also appear to be the only Demon of the Rift who isn't seen in the cutscene where Exdeath summons the demons.
Because Melusine constantly changes weaknesses and strengths with Barrier Shift, the battle can be a challenge. She uses elemental spells in their strongest forms. The form she changes into when she Barrier Shifts is weak to the spell she just cast—for example, if she casts Blizzaga then Barrier Shifts, she will be weak to ice magic. This is not certain however: sometimes she may cast Blizzaga but shift into her fourth form, fooling one into using Blizzaga against her only for her to absorb it. It might tie into whether or not she targets one or all (If she targets all, form #1 to #3. If she targets one, form #4).
The party should try to hit her with anything non-elemental, or use physical attacks. The player should watch for her to use strong spells and make sure at least one party member has a Flame or Ice Shield equipped to counter Firaga and/or Blizzaga.
With a party of Black Mages, one of which can summon, one can summon Carbuncle, then use Firaga on the party to reflect it to her, defeating her in only a few turns, before she can switch barriers. A Mystic Knight using Firaga Blade can also finish her before she changes her barrier.
Melusine is not immune to Confuse from the Dancer's Tempting Tango. She can also be put to Sleep, then attacked with magic to avoid waking her up.
[view·edit·purge]In European mythology, Melusine is a female spirit that inhabits or watches over water. Similar to a siren or mermaid, Melusine generally possesses one or more serpent or fish tails and a woman's torso and head. Sometimes she also has wings. Several noble houses took great pride in claiming to be descended from Melusine, notably the Plantagenet Dynasty of England.