Melusine (Final Fantasy V)

Melusine is a boss in Final Fantasy V. She is the first Demon of the Rift encountered. She possessed Lenna, but was thwarted.

Strategy
This battle will be pretty tough. She constantly changes barriers every so often and changes weaknesses and strengths. Your best bet is to hit her with anything not elemental like Bio or use your physical attacks because they seem to work pretty well. Keep your party's HP up and watch for her to use strong spells like Firaga or Blizzaga, so make sure at least one of your party members has a Flame or Ice shield equipped. Watch for what kind of attack she does, if she does a Fire attack use Blizzard or vice versa. Keep pounding on her until she's toast. Or, you can make your entire party black mages with one of them equipped with !Summon. Summon Carbuncle, then use Firaga on yourself to deflect it to her, defeating her in only a few turns. This will make the battle easier only if you are able to handle some damage. You'll probably defeat her before she switches barriers. If this doesn't work, try different third-tier magic.