The illusionist is an example of a specialist. The description of the
illusionist given here can be used as a guide for creating wizards specializing in
other magical schools.

First, the school of illusion is a very demanding field of study. To
specialize as an illusionist, a wizard needs a Dexterity score of at least 16.

An illusionist who has an Intelligence of 16 or more gains a 10% bonus to the
experience points he earns.

Because the illusionist knows far more about illusions than the standard
wizard, he is allowed a +1 bonus when rolling saving throws against illusions; other
characters suffer a -1 penalty when rolling saving throws against his
illusions. (These modifiers apply only if the spell allows a saving throw.)

Through the course of his studies, the illusionist has become adept at
memorizing illusion spells (though it is still an arduous process). He can memorize an
extra illusion spell at each spell level. Thus, as a 1st-level caster he can
memorize two spells, although at least one of these must be an illusion spell.

Later, when he begins to research new spells for his collection, he finds it
easier to devise new illusion spells to fill specialized needs. Research in
other schools is harder and more time consuming for him.

Finally, the intense study of illusion magic prevents the character from
mastering the other classes of spells that are totally alien to the illusion school
(those diametrically opposite illusion on the diagram). Thus, the illusionist
cannot learn spells from the schools of necromancy, invocation/evocation, or
abjuration.