Counter attacks in goddess form with Lullaby, Phantasm, Charm, and Doom's Kiss, so wait until it's an evil spirit. Attacks with Flash Rain, Bolt 2 and Bolt 3.
Chadarnook is a boss in Final Fantasy VI fought in Owzer's Mansion in the World of Ruin. It is a demon possessing a painting of the esperLakshmi, whose magiciteOwzer has stored in his bookshelf. Owzer bought the magicite at auction, and felt a need to have someone paint Lakshmi. Owzer hired various painters, but none were able to paint her to his satisfaction. When he heard of Relm Arrowny he hired her, but as she is painting, the demon tries to possess the artwork, and attacks the party.
For the North American SNES release, Chadarnook was censored and appears with more fog covering her body. While this change was reverted for the PlayStation, mobile, and Steam releases, she appears again with a differently censored sprite for the English Advance version.
Defeating Chadarnook in the mobile/Steam version earns the Portrait Time! achievement.
The Demon and the Goddess alternate. The Demon switches places when damaged five times or after a period of time, while the Goddess switches with the Demon when she takes enough turns in battle. Only the Demon can be killed; the Goddess regenerates if it runs out of HP. When the Demon falls the battle is won.
The Goddess counters most attacks with Phantasm, which inflicts HP Leak on the party, a status similar to Sap that cannot be cured and will continuously drain the party's HP. It can also use Entice to inflict a similar status to Confuse that cannot be cured. The Demon uses Thundara, Thundaga, and Flash Rain to attack. The Demon is weak to Fire and Holy.
The party must focus their efforts on the Demon. Any Lightning-absorbing equipment the party has will greatly reduce the threat. Firaga, Holy, Flare, and Ultima spells, as well as Blitz, Tools, Bushido, and Throw work well. When the Goddess appears, it is recommended to defend, since Phantasm can be annoying. When the Demon appears, an all-out offensive is in order. If Celes is in the party, she can be equipped with Dragoon Boots to use Jump on the Goddess and Runic on the Demon.