You're looking at a "Battlefield Controller" Wizard, methinks.
But if you're non too keen on traditional magic, you could do it with an Alchemist.
Funny I was just considering starting a thread labeled magic bullet about a four man party that can steamroll any encounter. Sadly I decided it was impossible so I didn't bother. This sounds like a similar premise, I will be interested to hear peoples response.
Either a grapple expert or a battlefield control expert. You could conceivably do both with a druid, although it might be tough to fit the feats in. Wizards are much better at aoe control, though, than either grapplers or druids.
One of my players had his character die in our current campaign and he worked with me to create a wizard that could do just this and no offensive spells (essentially we have a blaster sorcerer, so he wanted to create an abjurer/utility wizard to augment her abilities).
We went with Abjurer specialist, and added Thassilonian Specialist to give an extra spell slot (you can only memorize two of the same spell, but you still get an extra spell use!) We went with Charity as his focus instead of Envy as a bit of background info; i.e. the original magic system put forth by Xin instead of that corrupted by the Runelords. Same rules, different role-play focus.
Then the following Feats: Improved Counterspell and Skill Focus (Spellcraft) at first level, Spell Focus (Abjuration) at 3rd, Heighten Spell and Spell Specialization (Dispel Magic) at 5th, Preferred Spell (Dispel Magic) at 7th and Improved Initiative at 9th. Essentially, he goes before most casters. His high spellcraft means he usually doesn't have to roll to know what is being cast. If he has that spell memorized or one of the same school one or more levels higher, he can counterspell without making a dice roll (!) If he doesn't have that requirement, he casts dispel magic, either one of the two he has memorized in his bonus slots at third or trading it out spontaneously like a cleric with a spell third or higher. Because of his Specialization, he adds 2 to his caster level check meaning that he can counter enemy casters 2 levels higher than himself 50% of the time.
How effective is he? I had the drop on the party with an illusionist who was invisible, 3 levels higher than the abjurer, and had halucinatory terrain and other illusions to help hide in. He started hitting them with fireballs and the like—or would have, had the charity focused abjurer not identified every spell as it was being cast based on the verbal components and shut him down. Only one failed dispel roll allowed a single ice storm to affect the party. The rest was silence until the abjurer got the opportunity to dispel some of the illusionist's protective magic and the party warriors made mince meat out of him in less than a round. I had mixed feelings at this point: I was proud that my build ideas worked. I was a little disappointed that my illusionist got slammed without difficulty.
Note that some luck is still involved with dispel magic, but the better the caster is at the spell, the more powerful he is. When greater dispel magic comes along, he will be a regular beast! His other slots are filled with utility spells and protective wards to reduce or eliminate the effects of other spells, supernatural effects, and elemental damage.
Hope this helps!
Thanks for the info guys.
So using counterspells is the best way to shut the casters actions down?
Counterspell is the most effective, but with a few caveats. At low levels you won't be as effective as the Improved Counterspell only works when you have a spell one level higher in the same school as what is being cast. But once you get around 5th level, it really begins to have an effect. Remember, as long as you have a spell that can counter your opposing spell caster's spell it automatically counters the opposing spell. The only roll you make is to determine which spell is being cast, so a high Spellcraft is a must. Once you know and have readied a counterspell action, it's over. The spell is negated and the opposing caster is down one spell/slot. Then the fighter types have a field day.
And, you are very welcome! :)
Take a look at the switch class as an obtion here. I just build one for this exact purpose.
Another option, if you are specifically looking to shut down spellcasters, is the third party (Super Genius Games) class Witch Hunter. Had one in my Carrion Crown game and she basically curbstombed every encounter that involved casters - especially since at higher levels you are a full-BaB class with a high Will save who can Dispel Magic AND force any caster you threaten to take a -6 penalty on checks to cast defensively.
On the flip side, if you are looking for straight counterspelling, in the same game I had an oracle of Asmodeus who took the feat Ordered Mind, which is basically Improved Improved Counterspell. :p Being able to counterspell with a spell of the same level instead of one level higher means you should be able to shut down most spellcasters 100% of the time if you can make your spellcraft checks. Make sure you take Skill Focus Spellcraft to make up for the higher DC, and Improved Initiative to make sure you go first.
Ideally, be a Sorceror who worships Asmodeus and has the Arcane bloodline so you can take a Greensting Scorpian familiar for another +4 initiative. Then just make sure you know as many different schools of spells as possible and you'll be able to spontaneously cast just the right counterspell for the job. :)