If you begin as a specialist, then you have two banned schools at 1st level, then a 3rd upon taking Arcane Focus (formerly Enhanced Specialization) upon your first level of WoHS. Note that Diviners only have one school banned at 1st level, and 2 upon taking Arcane Focus.
If you don't specialize until you take Arcane Focus at 1st level of WoHS, then you lose only 2 schools (1 for Diviners).
I would recommend picking up Towers of High Sorcery for more info.
If you specialize in Divination at 1st level-Wizard, you only lose access to 1 school.
If you specialize in any other school at 1st level-Wizard, then you lose access to 2 chosen schools.
When you become a WoHS you may (or may not) choose to take Arcane Focus, if you were a specilaist in a school favored by your order then must choose to lose access to a school favored by one of the other two orders.
A little unclear about if you are a specialist in a school not favored by any of the orders. (Evocation and Conjuration), I would say treat as a non specialist by only take away 1 school)
If you were not previously a specialist prior to becoming a WoHS then you may take Arcane focus and lose access to 2 chosen schools (favored by the two other orders only), only 1 school if you decide to specialize in Divination (if you are a white robe)
So if as a wizard you choose not to specialize, and choose to when you become WoHS you must:
White Robes Choose:
Divination-Lose access to 1 school: either Illusion, Transmutation, Enchantment or Necromancy.
Abjuration-Lose access to 2 schools: either Illusion, Transmutation, Enchantment or Necromancy.
Red Robes Choose:
Either Transmutation or Illusion-Lose access to 2 schools: Either Enchantment, Necromancy, or Abjuration (Divination cannot be chosen as a banned school)
Black Robes Choose:
Either Necromancy or Enchantment-Lose access to 2 schools: Either Transmutation, Illusion or Abjuration (Again Divination cannot be chosen as a banned school).
If you choose to specilize at 1st level wizard. (Divination cannot be chosen as a banned school)
Abjurers-Lose access to 2 schools: Conjuration, Enchantment, Evocation, Illusion, Necromancy, Transmutation.
:Who becomes a White Robe-May choose arcane focus-Lose access to either Enchantment, Illusion, Necromancy or Transmutation (if not previously chosen).
:Who becomes a Red Robe-? (No change)
:Who becomes a Black Robe-? (No change)
Conjurers-Lose access to 2 schools: Abjuration, Enchantment, Evocation, Illusion, Necromancy, Transmutation.
:Who becomes a White Robe-? (No change)
:Who becomes a Red Robe-? (No change)
:Who becomes a Black Robe-? (No change)
Diviners-lose access to 1 schools: Abjuration, Conjuration, Enchantment, Evocation, Illusion, Necromancy, Transmutation.
:Who becomes a White Robe-May choose arcane focus-Lose access to either Enchantment, Illusion, Necromancy or Transmutation (if not previously chosen).
:Who becomes a Red Robe-? (No change)
:Who becomes a Black Robe-? (No change)
Enchanters-Lose access to 2 schools: Abjuration, Conjuration, Evocation, Illusion, Necromancy, Transmutation.
:Who becomes a White Robe-? (No change)
:Who becomes a Red Robe-? (No change)
:Who becomes a Black Robe-May choose arcane focus-Lose access to either Abjuration, Transmutation, or Illusion (if not previously chosen).
Evokers-Lose access to 2 schools: Abjuration, Conjuration, Enchantment, Illusion, Necromancy, Transmutation.
:Who becomes a White Robe-? (No change)
:Who becomes a Red Robe-? (No change)
:Who becomes a Black Robe-? (No change)
Illusionists-Lose access to 2 schools: Abjuration, Conjuration, Enchantment, Evocation, Necromancy, Transmutation.
:Who becomes a White Robe-? (No change)
:Who becomes a Red Robe-May choose arcane focus-Lose access to either Abjuration, Enchantment, or Necromancy (if not previously chosen).
:Who becomes a Black Robe-? (No change)
Necromancers-Lose access to 2 schools: Abjuration, Conjuration, Enchantment, Evocation, Illusion, Transmutation.
:Who becomes a White Robe-? (No change)
:Who becomes a Red Robe-? (No change)
:Who becomes a Black Robe-May choose arcane focus-Lose access to either Abjuration, Transmutation, or Illusion (if not previously chosen).
Transmuters-Lose access to 2 schools: Abjuration, Conjuration, Enchantment, Evocation, Illusion, Necromancy.
:Who becomes a White Robe-? (No change)
:Who becomes a Red Robe-May choose arcane focus-Lose access to either Abjuration, Enchantment, or Necromancy (if not previously chosen).
:Who becomes a Black Robe-? (No change)
So you see, it depend on 5 factors. 1: Whether you choose to specialize as a 1st level wizard, 2:What you specialize in, 3:If you decide to specialize after becoming a WoHS, 4:Whether you decide to further specialize (if you specialized as a 1st-level wizard), and 5: What order you belong to.
So you could have 0 to 3 banned schools.
0-If you do not specialize at all.
1-If you are a diviner and do not further specialize, or become a Diviner after becoming a WoHS.
2-If you are a diviner, and become a White Robe, and decide to further specialize, or become a Specialist after becoming a WoHS, or are a Speciallist who decides not to further specialize.
3-If you are a specilist (other than a Diviner), and decide to further specialize.
Examples:
Evoker that chooses to lose access to Abjuration and Illusion, who becomes a WoHS, does not have the option of further specializing.
Illusionist that chooses to lose Necromancy, & Evocation and becomes a Red Robe and chooses to further specialize must lose access to either Abjuration or Enchantment (the only schools favored by the other orders not previously chosen as banned schools).
Necromancer that chooses to lose access to Transmutation and Illusion and becomes a Black robe, if he want to further specialize he must lose access to Abjuration (the only school left that is favored by one of the other orders [remember, Divination is not an option as a banned school-ever!!!] and that has not been previously chosen as a banned school)
A generalist Wizard that becomes a White Robe and wants to focus in Abjuration must lose access to 2 of the following schools: Illusion, Transmutation, Necromancy and Enchantment.
Hope I didn't confuse you. :surrender
