C♯13 (also written D♭13) is a dominant thirteenth chord made of 6 notes: C♯, E♯, G♯, B, D♯, A♯. It sounds full and jazzy, the most colourful dominant chord, and you hear it in jazz, blues and big-band endings. It is the V chord of F♯ major and turns up in 2 other keys.
The library above opens on C♯13 with 14 shapes up and down the neck. Tap a shape to hear it, or play it one string at a time.