Mehhhh.

Prerequisites:
Base Attack Bonus: 8+
Feats: Blind-Fight (PHB), Mage Slayer(CAr), Peirce Magical Concealment (CAr), Pierce Magical Protection (CAr)
Special: Must belong to a group dedicated to fighting spellcasters.
Level BAB Fort Ref Will Special
1st +1 +2 +0 +2 Shatter Spells
2nd +2 +3 +0 +3 Disrupting Strike
3rd +3 +3 +1 +3 Hidden Slayer
Alignment: Any
Hit Die: 1d10

Class Skills:
The spellshater's class skills (and the key ability for each skill) are Bluff (Cha), Craft (Int), Gather Information (Cha), Knowledge (Arcana) (Int), Profession (Wis), Sense Motive (Wis) and Spellcraft (Int)
Skill Points at Each Level: 2 + Int modifier

Weapon and Armour Proficiency
The Spellshater doesn't gain any proficiency with any kind of weapons or armour.

Shatter Spells (Su)
A spellshatter has the ability to dispel beneficial spells of those it attacks. When the spellshatter strikes a creature with one of more beneficial spells on, first check to see if the spellshatter's other abilities, such as Pierce Magical Protection, dispel any of these spells. Then, for each spell, add the caster level and spell level together. This is the resistance total for that spell. Check to see how much damage the spellshatter's attack deals, this becomes the dispel total.

If the dispel total is the same as or higher than the resistance total of the spell with the highest resistance total, dispel that spell and then reduce the dispel total by the spell's resistance total. If the dispel total is lower than the resistance total of that spell, instead dispel the spell with the highest of those resistance totals which is below the dispel total, and reduce the dispel total by that resistance total. Repeat this process until the dispel total is lower than the lowest resistance total or there are no spells left to dispel; any further dispel total is wasted.

(For example, if a spellshatter deals 30 damage to a creature with three spells of resistance totals 16, 15 and 14 active, the spell with resistance total 16 is dispelled, then the spell with resistance total 14 which is equal to the attack's remaining dispel total. This is true even if the first spell was a caster level 15 first-level spell and the second was a caster level 10 fifth-level spell!

If it helps, this process uses the first-fit descending algorithm.)

Disrupting Strike (Ex)
From second level, it's not possible to concentrate on a spell when damaged by the spellshatter during the casting.

Hidden Slayer (ex)
From third level, the effects of the mage slayer feat are hidden and creatures do not know that they can't cast defensively in the area. They can even try to: they just won't succeed.