Archeodemon is an optional boss fought in the Sealed Temple in the Game Boy Advance and later releases of the game. It is an undead demon that will counter any non-magic attack with Death on itself to revive at full HP, and absorbs all elemental damage except Holy. It attacks with exceptionally powerful skills such as Megaflare, Gigaflare, ????, and Curse.
Archaeodaemons are fearsome foes, yet still weaker than their counterparts, the Ultima Demon. They are fought during the battle with Belias and with the undead Zalbagg, and fight using powerful abilities such as Unholy Darkness, Gigaflare, and Lifebreak. They are immune to Holy-elemental attacks.
The prefix arch-, as in "archangel" or "archvillain," comes from Greek arkhos meaning "most important."
demon is "an evil spirit or devil, especially one thought to possess a person or act as a tormentor in hell."A