How do I get up to the wizard's desk?

It would help if you had something to climb on.

One of the things that Magician can do is to make plants grow.

There are two plants near the wizard's desk that Warrior could climb on,
if only they were tall enough.

So have Magician cast his spells on the plants -- specifically, the left
of the two.  You'll lose energy if you "spell" the one on the right.

Now the warrior can climb up the left plant and get to the desk.  The
only problem is that the right plant would like to eat our warrior.

So perhaps you should feed the plant.  The wizard must have some food
in his place somewhere.