Blast the skeleton!

You need but a moment to decide what to do. First you will make sure you are in no danger, then you can worry about examining the doors and the rest of the room.

You point your staff at the skeleton and shoot an arrow of white energy at it. As soon as the projectile hits it the undead guardian explodes in a cloud of dust while its sword and shield fall down to the floor.

As you watch the sword, shield and cloud of dust all vanish without a trace. The only thing left behind is a small silver key that was under the shield. You wait for a few more seconds before deciding that you are in no further danger and picking up the small key.

With the skeleton gone you turn your attention to exploring your surroundings. Immediately you notice two things: The door through which you entered the room is gone, and there are now five wooden doors instead of the two you saw earlier. The floor, ceiling and walls are all made from gray stone – completely unremarkable, as far as you can see. So you turn your attention to the five doors.

They turn out to be identical wooden double doors, with the only visible difference being the symbols engraved on them. On the left-most door you see the engraving of a mountain, on the second – an eye, on the middle one – a book, on the fourth one – a coin, and on the right-most door – a chest. Further examination reveals no additional information. Looks like you'll have to guess what – if anything – the symbols mean...