What is the hard way?

Hint 1 of 6:

If you go to the Realm of the Dead, you will be taking the hard path.  See
the Druids on the Isle of the Mist to help you enter this Realm.

Hint 2 of 6:

You will need to use a spell to get back in.  One of its ingredients can only
be found in the Realm of the Dead.

Hint 3 of 6:

Sometimes, wishes can come true.

Hint 4 of 6:

You can create your own entrance into the castle.

Hint 5 of 6:

The magic paint spell will let you do that.

Hint 6 of 6:

There's a nice blank wall on the castle just off to the side.