How about some fun for DnD 5e? Haven’t done that in a while, but I think it’s time to do a fighter build. Let’s make one that hunts magic users!
You hate magic. You’ve studied long and hard to make those who use it pay. Be it the evil wizards who may have enslaved your family, the vile cleric who sacrificed your parents, or the capricious warlock who seduced your lover-you hate all who use the art. Now, you’ve honed your weapons, more specifically your hammers, to deal with those who cast spells. You’ve suffered, and now they’re going to pay!
At 3rd level, you’ve mastered the art of distraction. When you are engaged with any spell casting creature and they cast a spell, you can spend a reaction to force them to make a Constitution saving throw with the DC equal to 8 + your proficiency bonus + your strength or dexterity modifier. If they fail, they lose the spell.
At 7th level, you have mastered the art of spell resistance. You gain advantage on all saving throws against spells cast against you. You can choose when this effect is applied, and if you want to make a saving throw at all if you are aware of the spell.
At 10th level, when you strike a foe with a hammer or hammer-like weapon that does bludgeoning damage and the foe tries to cast a spell, they gain disadvantage on the Constitution saving throw from your Magic Dissonance class feature.
At 15th level, if you succeed at a saving throw and the spell would still affect you even if you succeed, you are now no longer affected by the spell at all. If you fail a saving throw against a spell and the spell has an effect on a success, you are only effected by the effect of the spell as if you had succeed on the spell saving throw.
The True Spell Hammer
Starting at 18th level, you no longer have to spend a reaction to use your Magic Dissonance class feature.