Illusionist's Gambit (Patreon)

Wondrous item, uncommon

This eye-shaped brass coin depicts an open iris on one side (heads) and a blackened, scratched-out one on the other (tails). While holding it, you can use an action to speak the coin's command word. Then, flip the coin. If it's tails, you vanish and become invisible until the start of your next turn. If it's heads, nothing happens. Continue to flip the coin again at the start of each of your turns for 1 minute (no action required). The effect ends early if you make an attack or cast a spell while you're invisible. It also ends early if you're incapacitated or are otherwise unable to flip the coin at the start of your turn.

The coin can't be used again until the next dawn.

The only guard on gate duty was almost asleep. Nobody came to the vault level anyway, so…

He clattered to attention as a flash of brass spun out from the corner, a concealed form grabbing for it before—

The hall was empty, only a quiet breeze passing through. He settled back, reasoning the best counter to his obvious sleep deprivation was more sleep.

He never saw the figure blink into visibility behind him, a grin plastered across her face.