Mighty Storm's Aspects a Druid Offensive Aspect that can only be found from random drops. Unlike Codex Aspects you can't go run a Dungeon to unlock this and will have to rely on RNG.
How to Obtain - Drop Only - No Codex Available
Mighty Storm's Aspect Mechanics
Legendary Aspects can change the way skills and builds work in significant ways.
Mighty Storm's Aspect enables Earthen Might to also apply to Storm Skills, providing opportunities for synergies that were not possible without it.
For further information, see our Build Guides, Legendary Aspects & Codex of Power
Mighty Storm's Aspect