From Final Fantasy XIV A Realm Reborn Wiki
Thunder III is an action unlocked by questing at level 45. It's available for Black Mage.“
Deals lightning damage with a potency of 70.
- Additional Effect: Lightning damage over time
- Potency: 40
- Duration: 24s
- Additional Effect: 10% chance after each tick that the next Thunder spell of any grade will add its full damage over time amount to its initial damage, have no cast time, and cost no MP
- Duration: 18s
- Only one Thunder spell-induced damage over time effect per caster can be inflicted upon a single target.
— In-game description