The objective of the The Miser's Will event is to open the "right" chest among a group of three. Your success is purely based on luck. There is a bonus if you open the right chest on the first try. This event takes place in the Miser's Hovel in the Westmarch Commons in Act V. Note the nice pattern in the center of the room.
This is one of the events to be completed to obtain the "Sightseeing" and "The Tourists" Achievements.