What do I do at the Statue of Serenity?

Remember that "X" marks the spot.

Magician's spells might have a different effect when used there.

And Magician can turn the stone into a larger stone.

Get the stone and put it on top of the "X".  Then have Magician cast a spell
on it twice to make a ladder.

You'll be able to get up to the statue now.

The pendulum you brought from the last screen is important, so try using it
in different locations.

When you use it near the middle of the screen, it will shake violently.

Now, you need to do something to find out what's making the pendulum shake.
Magician can create a tool to do that if you have him use his magic in the 
right place.