Void Knight

Some people are born without spellcasting abilities. However these select few tend to take up arms and defend the helpless of the scourge of dark mages and their powers. Sometimes called witch hunters or inquisitors, the Anti-Magic Warriors are specialized in fighting against magical creatures and are trained to even the battlefield with the ability to cancel spells.

Arcane Savant

When you choose this archetype at 3rd level, you gain proficiency in the Arcana skill, if you don't already have it. Your proficiency bonus is doubled for any ability check you make that uses this proficiency.

Spell Breaker

At 7th level, you learn how to interrupt an creatures spell casting. When a creature is casting a spell within the reach of your meele weapon, you can use your reaction to make an attack against the creature. And if the attack hit, the creature must make a concentration saving throw with DC of half the damage dealt rounded down.

(If you have the Mage Slayer feat the DC is increased by 2 and you make the attack at advantage)

Arcane Sense

At 7th level, you have the ability to sense magical auras, as in the detect magic spell, that you can manifest in the following: a 30-foot cone; a 15-foot radius sphere; or a 60-foot long and 5-foot wide line. You can activate your Arcane Sight as an action, and, when active, it lasts for 10 minutes. In addition to magical auras, when used to look at a creature, you learn if the creature is capable of casting spells. You can use this feature a number of times equal to your Proficiency bonus. Once you spend all your uses, you can't use it again until you finish a long rest.

Magic Resistance

You have advantage against all spells and magic effects. When you successfully make a save against a spell cast on you regain hit point equal to 1d10+fighter level.

There is a 25% chance that potions will fail to work on you. Along with allies casting spells on you.

Evasion

When you successfully make a Constitution saving throw again a spell or effect to take half damage You instead take no damage.

Limited Magic Immunity

You cannot be effected by spells lower than level 5.But that applies to allies too. There is a 50% chance that potions do not work on you. And magic items can fail to function.

Null field

Once per long rest you can radiate your anti magic to suppress magic around you. You can activate the field as a bonus action and for 10 mins 15ft around you is considered an anti magic zone.