Maliris

Maliris (a mistranslation of Marilith) is a boss from Final Fantasy IX. The party fights it in Memoria.

Maliris is first encountered by the party in the Fire Shrine. While she isn't fought then, she does challenge Freya and Amarant and they appear to have fought her to place the mirror.

Maliris appears again in the Memoria on the bridge leading to the memory of Alexandria being destroyed.

Strategy
Maliris likes to use Fire magic on the party and especially with her sword attacks. Ice and Water magic is useful here, as are Eidolons such as Shiva and Leviathan. Maliris also likes to cast Mustard Bomb on the party, which inflicts the Heat status. Quina can learn this technique from her, but it can be learned from a variety of other creatures, as well. She casts Reflect on herself and will reflect Fire spells off herself to hit the party. By now, all characters should have Auto-Reflect, so don't Dispel it from her, just reflect Blizzaga or Water off of a character, or the whole party for a stronger effect. Make sure that Zidane steals all the items that she has, as they are very hard to find. Most of the party must have their HP almost fully healed by the end of the battle because, when defeated, Maliris attacks with Raining Swords that will do about 4000 HP to all characters.

Crystal World Incarnation
The translucent form of Maliris is considerably weaker, as she does not perform Raining Swords upon her defeat and has a substantially lesser amount of HP. A constant barrage of Ice-elemental magic and physical attacks charged with the Demon Killer ability should be enough to bring this snake down quickly.