Now what's next?

Hint 1 of 11:

Remember that the wizard changes forms every time you attack him.

Hint 2 of 11:

I would suggest that you use the character that will encourage the wizard
to change forms, just in case.

Hint 3 of 11:

Have Magician cast a spell on the wizard, and he'll turn in to a bunch of
little spiders.

Hint 4 of 11:

You'll need to catch those little spiders and get rid of them before they
pose a threat again.

Hint 5 of 11:

The only way I found to do that was to be prepared for the spiders to land.
If you're not, you'll have to repeat this sequence until you get it right.

Hint 6 of 11:

You will need a container for the spiders.

Hint 7 of 11:

Drop the empty bag just below the spider before you cast a spell on it.

Hint 8 of 11:

It's time to take care of the wizard, now that he's trapped in your bag.