From Final Fantasy XIV A Realm Reborn Wiki
Mythril Tempest is an action unlocked by questing at level 40. It's available for Warrior.“
Delivers an attack with potency of 100 to all nearby enemies.
- Combo Action: Overpower
- Combo Potency: 200
- Combo Bonus: Extends Storm's Eye duration by 10s to a maximum of 30s
- Combo Bonus: Increases the Beast Gauge by 20
— In-game description