I couldn't finish 'em. Looks like this's gonna get complicated.
Elgo is the second-to-last boss in Final Fantasy Dimensions. The battle is divided into two parts. As the Warriors of Light and Darkness reach the Edge of the World of Nil, they come across Elgo sitting at his throne who explains that he is the Emperor of the Avalonian Empire, and was seeking the crystals out to defy death and rule to the end of days instead of gaining temporal power. The heroes learn that the crystals caused a dimensional shift and divided the world so as to remain safe from Elgo. The Warriors refuse to hand the crystals over, causing Elgo to show them the Power of Nil.
Elgo is fought in two stages. In the first he uses mostly high level magic. He will at first use Flare, Holy and Comet, and continue either of them with Slice n' Dice. His spells can do several thousand damage, around 3000–4000 each, and Slice n' Dice can hit for above 1000. At this stage he infrequently counters attacks with Slow.
After half his HP has been depleted the second stage starts with a sprite change and he gains access to Pandora's Box, which allows him to employ one of three high level elemental magic to hit the entire party. Neutrino deals fire damage, Axion deals ice damage and can inflict Stop. Neutralino deals lightning damage and can stun. Elgo's Magic Blade command from the Red Mage job uses the likes of Arcish Slash and Freezing Slash as a stronger Slice n' Dice. He counters attacks with Gravity, which halves a character's HP. Later on he casts Meteor and Ultima, the latter of which can deal 3000 damage to the party with Shell on.
The party should be well-leveled (70+) and geared as this boss can be difficult due to his high HP since the last boss and his deadly arsenal of moves. The player should come prepared with at least two healers. Seers are a good choice and preferably equipped with the Hermes Sandals found in the dungeon. Other preparations include learning some power moves like Saber Dancer, which can be learned in Castle Lux, as well as some of the game's most powerful Fusion Abilities like Mighty Wall, Hastega, Final Heaven, Midareyuki, and Phantom Rush, as they can inflict great damage. Supplies like Dry Ethers or X-Potions are also a good idea.
The player should set as many buffs as possible. One healer should focus on healing while the other buffs, as Elgo can kill characters quick if defenses are not ready. The attackers should use their strongest attacks and use an Ether or a Dry Ether if they run out of MP. For the healing tasks Seer are a good idea due to their high INT and MP values. Since the player is likely to consume a high amount of MP, the Warrior and Monk, while durable, are not good as their MP values are low. The player should waste the least time on restoring MP as possible and spend more time on the offensive.
Once Elgo hits the 50% HP threshold he will become more aggressive with his attacks using Pandora's Box for major elemental damage. Gravity can be annoying since it can be followed with a strong attack, so the player should keep both the healing and buffs at all times. The Hermes Sandals helps, as it almost guarantees the healer can heal between attacks. Tetra Bangles can help in keeping the damage from many of his attacks at bay since they fall on the categories the accessory protects against.
At near 3/4 of his HP gone, Elgo may use Ultima, his strongest attack that is likely be fatal to those without any protection. As long as the player keeps the high damaging attacks going Elgo should fall soon, as most of the difficulty comes from Elgo's strong attacks while being resilient.