Fire damage on all opponents
Beta can be learned as an Enemy Skill. It is a difficult spell to obtain when it first becomes available since it is the signature spell of the monster Midgar Zolom, fought outside the Mythril Mine soon after the party first leaves Midgar. The party member with the Enemy Skill Materia must withstand the attack and not be ejected from battle to learn it. Midgar Zolom uses Beta when it is on its last quarter of health.
The simplest way to learn Beta early is to equip an Elemental Materia in a linked slot with a Fire Materia to reduce Beta's damage to approximately 600, allowing a character with high enough HP to survive it. The character can then cast Beta to kill the Midgar Zolom, and end the battle with Beta learned. The character with this set-up should not attack once the Midgar Zolom rises into the air, so it is less likely to eject them.
It takes 35 MP to cast. The spell's graphic is akin to that of a nuclear bomb exploding with a resulting mushroom cloud.
Beta (uppercase Β, lowercase β; Greek: Βήτα Bḗta) is the second letter of the Greek alphabet.