There will be four Crystals in this battle; the top one is Fire-elemental, the right Water-elemental, the left Wind-elemental, and the bottom is Earth-elemental. Each fights with normal attacks, and after a significant amount of HP is reduced, it uses a high level attack of its corresponding element that damages all targets: Crystal of Fire will use Firaga, Crystal of Wind uses Aeroga, Crystal of Water uses Aqua Breath, and Crystal of Earth uses Earth Shaker.
For quick way to defeat the Crystals the player should learn Aeroga for a Blue Magic, summon Golem, and then use Gil Toss. The player should target the Wind Crystal to put it below 3,000 health, and after it uses Aeroga, use Gil Toss again.
If the player took the trouble to acquire Death Sickle(s) in Bartz's World, the party members that can wield axes can potentially OHKO the Crystals one by one. This can be bit of a gamble, especially when done with Berserkers, as the Death Sickle has merely a 33% chance of inflicting instant death and the player cannot control Berserker actions. There is a risk that the Berserkers damage the Crystals too evenly, which may lead to multiple of the Crystals start using their high level elemental attacks and devastating the party.
In the Cloister of the Dead in the Advance or mobile remake, when fighting the Crystals again, the player may opt to use Odin to instantly kill all four Crystals at once.
The Crystals were not named in the original Super Famicom and PlayStation versions, displaying their names blanked in the battle UI. In the Game Boy Advance and mobile versions they were called "????" in battle and "Crystal" in the bestiary.