The coin appears to be a blank, unstamped copper coin. If a statement is made about a course of action and the coin is flipped, upon landing the face will reveal one of two images: an angelic scene if the course of action is advisable or safe, or a demonic scene if the action is ill-advised or dangerous. The statement must be phrased as a course of action to activate the coin's magic, i.e., "We will trust what this merchant says"; "We will take the left corridor"; "I will drink the contents of this bottle." If the outcome of the action is unknown/questionable or if a question is asked ("Should we take the left corridor?"), the coin will remain blank upon landing, offering no input one way or another.
The Boon/Bane Coin's magic works in a manner similar to the 5th level Cleric spell Commune, though the coin is not beholden to any specific deity. The Boon/Bane Coin will reveal two answers per day. Further daily demands upon the coin will result only in blank faces.