Aspect of Audacity is a Legendary 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
Aspect of Audacity Mechanics
Legendary Aspects can change the way skills and builds work in significant ways.
For further information, see our Build Guides, Legendary Aspects & Codex of Power
Aspect of Audacity