The Well Wisher

From the introduction: When someone throws a coin into a wishing well the intense desire, longing, pain or sorrow of the person imbues the coin with a fragment of magical energy. Sometimes there is enough energy to make the wish come true. Other times though, the coins gather at the bottom of the well with their magical energy unspent. They sit, wait, attract. Foul creatures exist that feed on the unspent energy, the sadness, infused in these coins.