Prohibited Schools for Illusionists?

[Temotei]

What would you recommend not taking for schools when specializing in illusion? So far, I've got necromancy barred, but I'm stuck past that. I'm leaning towards conjuration right now.

[Gralamin]

What would you recommend not taking for schools when specializing in illusion? So far, I've got necromancy barred, but I'm stuck past that. I'm leaning towards conjuration right now.

Evocation. You can pretty much mimic anything good from the school ANYWAY with illusion spells.

[lsfreak]

On the one hand, enchantment goes hand-in-hand with illusion with "mind-tinkery". On the other hand, there's a bit of overlap and illusion doesn't suffer the same weakness as enchantment (like not affecting mindless creatures and being knocked out by a 2nd-level spell).

Necromancy overlaps with a lot of the debuffs that illusion deals with, though giving up Enervation and a few others can hurt.

If there's another caster, Abjuration can go if you need it to. As long as someone can cover dispel magic you should still be okay.

Don't trash Conj or Trans unless you have a really good background reason to. Just about the only things those two can't do are the really good defenses (that's Illusion) and divinations (can't ban it anywho). They've got the really heavy-hitting battlefield control, damage, combat buffs, and utility buffs.

EDIT: Well, and of course Evocation. I actually managed to forget about it Illusion (through Shadow Evocation) and Conj (Orb line, among others) cover it fine though.

[sonofzeal]

Enchantment should be top of the list to ban for Illusion. The majority of the offensive potential of both schools falls under "Will Negates SoL", and that's a pretty narrow niche.

The insta-ban of Evocation is a pet peeve of mine. I think the school's been underrated, partially because people associate it with blasting, and partially because it generally competes with Conjuration (arguably the best school in the game). Still, if you've got Illusion and Conjuration, you don't need Evocation.

If you have a good Cleric or Druid in the party, I'd ban Abjuration. Most of the nice spells there are also on the divine lists, and they don't need to waste spellbook slots on it. If you don't have a good Cleric or Druid, I'd ban Necromancy. Not that Necro isn't a good school, but it's one that can get your character in trouble depending on the setting and is generally the most likely to be out of character for non-evil Wizards.

[Temotei]

The other caster is a cleric with the Healing and Strength domains. The party is starting at 6th level, ending at around 12th, if all goes to plan. That should help some. Any changes? Thanks for the help, guys. And the fast responses.

EDIT: Also, we're all hoping to stay good. We have a homebrewed alignment system that acts in accordance to what you do, with no solid names for what you are.

[The Gilded Duke]

Illusion is the most powerful battlefield control school ever.
Yes a lot of its abilities are will negates, but there are a few specific differences that make it worthwhile.

Very few figment spells (the image line) are affected by spell resistance.
People only get to make a save against illusion spells if they interact with them.
Interaction or studying of an illusion takes a standard or move action.
Mindless creatures cannot interact with an illusion to attempt to disbelieve.

Lets take a look at Silent Image
http://www.d20srd.org/srd/spells/silentImage.htm

1st level spell, duration concentration.
Can create 10 foot cubes of silent illusions, Four + One per every level.
Make an illusion that blocks line of sight, like a wall.

You just forced 4+1/level enemies to waste a move or standard action in combat before they even got a save.
Or you just shut down 4+1/level Oozes, unintelligent Undead, or Golems.

Now the main problem with illusions is True Seeing, however as a 5-6th level spell it will not be cast on every opponent.
When it does come up however, dispel magic is your friend, so I'd keep abjuration. Transmutation and Conjuration are useful schools for non-illusion battlefield control.

Take out the enemy cleric with True Seeing with a Sleet Storm, and then use Silent Image to take out the rest of the enemy party for example.

Now the main advantage that illusions have over Sleet Storm and Walls and so on is that you can tell your party that they are not real. Give your party total concealment, and block your enemies line of sight and line of effect.

So to summarize:
Ban Enchantment
Don't Ban Abjuration or Transmutation
Conjuration is nice to keep, but can be emulated.

[The Gilded Duke]

As far as necromancy, it has some useful debuff spells, and Magic Jar does some enchantment like things. Have you checked out the Gnome Illusionist levels in Races of Stone? The first level bumps most of your figments down a level. (Shutting people down with a 0 level Silent Image is awesome)

The fifth level automatically extends your illusion spells or adds additional rounds to concentration duration spells. There is also Spell Focus Illusion, Greater Spell Focus Illusion, a Forgotten Realms Gnome Feat which is basically an additional Spell Focus Illusion. Master Specialist also has some real nice effects for Illusion and can be entered at 5th level.

Shadowcraft Mage from Races of Stone is perhaps too awesome to actually play.

[lesser_minion]

If I was DM'ing, I'd advise you against banning Evocation, mainly because I personally consider Greater Shadow Evocation: Contingency to be mildly cheesy. Several of the other good evocations cannot actually be mimicked by illusions (SE: Wind wall won't actually provide a defence against archers).

I also ban Craft Contingent Spell, because it is insanely powerful.

I'd suggest making sure that you actually can do without the good evocation spells before banning the school, or at least check how it will affect your access to the spells with your DM.

[Amphetryon]

Enchantment and Necromancy are the standard choices for an Illusionist to ban IME. Evocation is the other solid choice, but there's something amusing about mixing and matching real with illusory kabooms.

[Temet Nosce]

I'll say the obvious thing. Ban Evocation, essentially everything in this school is replaceable and I don't mean with shadow evocation (in many cases not only replaceable, but the replacements are flat out better). The school simply provides you with nothing unique.

My second suggestion, don't ban Enchantment unless you aren't playing this character at low levels at all. You will get more use from this school than the others put together at low levels (encounter enders, social spells, etc). At high levels immunity will give you headaches so it's less useful, but till stuff starts being immune it's absolutely incredible.

Also, never ever ban Conjuration. Just... don't. To much in there.