This silver coin appears wholly unremarkable to any casual inspection (although a knowledgeable numismatist would most likely be puzzled by the fact that its decorations do not appear to match any known coinage).
When placed in close proximity with other coins, however, the Coin of Icarus will imbue a random number of its fellow coins with an anti-gravity field. The most common effect is for its owner to open their coin purse only to have a half dozen or so coins suddenly fly out and disappear into the sky above. (Although it’s not entirely unheard of to find a Coin of Icarus lying amidst a scattering of random coins on the floor of some ancient vault, while a hundred or more coins have seemingly glued themselves to the ceiling.)
The Coin of Icarus will randomly afflict 2d6 coins per week, although on some occasions it will become much more vigorous in its uncanny effect: If the 2d6 roll results in a natural 12, re-roll the dice and add the new result (repeating indefinitely for as long as natural 12s are rolled).