In return for opening the jail, I'll rip you limb from limb! Whatta deal!
Archeodemon uses Drain Touch and Flare, and like Twintania, will charge up and cast Mega Flare for major damage. Unlike Twintania, it does not become vulnerable to Odin during this period. Once its HP is reduced to 15,000, it will charge up for Giga Flare, which deals even greater damage; once he drops below this threshold, the party must attempt to kill it as quickly as possible.
If attacked physically, Archeodemon will cast Death upon itself, and due to being undead, this will heal itself completely. Phoenix Downs and the Raise spell will fail on it, and it absorbs all elemental magic (including Holy). Archeodemon can counter with Curse or ????, which, given his enormous HP, is likely to kill the target.
The party should focus on dualcasting its most powerful non-elemental spells, namely Flare, Meteor and Bahamut. Meteor is recommended, as the damage dealt by the four-hit combo will accumulate quickly due to Archeodemon's negligible Magic Defense.
One way to defeat Archeodemon is to equip Bone Mails and cast Reflect on Archeodemon, so the party can attack with their most powerful physical techniques and Archeodemon will reflect Death on the party, but while wearing the Bone Mail it will not hurt.
To defeat it without much trouble, the party can drain its MP via using an Ether on it first (setting its MP to 9999), then spamming the Blue Magic Magic Hammer. Once its MP is down to 0, Archeodemon will no longer be able to cast Death nor any spells outside of Mega Flare or Giga Flare. It can then be brought down with most non-elemental attacks easily.
Another way to defeat it without any trouble is to cast Mute so it will be unable to use his Flare or Death. The party can use Rapid Fire. This is quicker than using Magic Hammer to drain its MP to 0.
Another method is to have everyone be a Mime with an Angel Ring equipped. One member should have the Dualcast, White Magic and Summon commands. This member should cast Curaga upon the party, then summon Bahamut and have all party members mimic this until Archeodemon dies.
Other appearances Edit
The word root archaeo-, as in "archaeology," comes from Greek archaios meaning "ancient."
demon is "an evil spirit or devil, especially one thought to possess a person or act as a tormentor in hell."A