C♯aug (also written D♭aug) is a augmented chord made of 3 notes: C♯, E♯, G𝄪. It sounds eerie and expectant, and you hear it in a step between a chord and the next, for example in a rising line.
The library above opens on C♯aug with 14 shapes up and down the neck. Tap a shape to hear it, or play it one string at a time.