Monks who follow the Way of the Mage Hunter dedicate their lives to hunting down and stopping those evil magic users who would use their powers to plague the world.  Where other might choose the path of brute force or impenetrable defense, the Mage Hunter choose to turn their adversaries strengths against them.  When one man holds the power to lay waste to entire armies in the palm of his hand the Mage Hunters hold the ability to turn that power back in upon itself.

Deflect Spell

Starting at 3rd level, you can use the power of your ki to try to redirect spells directed at you.  If a creature that you can see make a spell attack against you can use your reaction to spend a number of ki point equal to the spell's level to make a DC saving throw equal to 10 + spell level (cantrips count as a 1).  If you pass the saving throw you can redirect the spell attack to another target(including the spellcaster) within the spell's range or to an empty space where it dissipates.  If you choose redirect the spell at another creature make a spell attack roll using your wisdom modifier + your proficiency bonus.

Manhandler

One of the best ways to deal with a magic user is to separate them from their protectors.  Starting at 3rd level you gain advantage on grapple checks and proficiency in Athletics.  If you already have proficiency in Athletics you instead gain expertise in Athletics.

Spell Sabotage

Starting at 6th level, you master the art of interrupting spells with your unarmed strikes.  If an enemy within 5 feet of you attempts to casts a spell you can use your reaction to  spend 1 ki point to make an unarmored Stunning Strike against the spellcaster.  If the unarmed Stunning Strike hits, the spellcaster has disadvantage on its constitution saving throw against the Stunning Strike.  If the spellcaster fails its constitution saving throw against the Stunning Strike the spell fails and spellcaster is stunned until the start of its next turn.

If you hit a creature that is concentrating on a spell with an unarmed strike, that creature has disadvantage on the saving throw it makes to maintain its concentration.

Spell Absorbtion

Starting at 11th level, you learn to absorb nearby spells to refuel your own spiritual energy.  When a creature that you can see within 60 feet of you cast a spell, you can use your reaction to make an ability check using your wisdom modifier + proficiency bonus.  The DC equals 10 + the spell's level. On a success, the creature's spell fails and you regain ki points equal to the spell's level up to your maximum ki points.

You can use this feature a number of time equal to your wisdom modifier per long rest.

Improve Deflect Spell

Starting at 11rd level, you can use the power of your ki to try to redirect spells directed at your allies.  If a creature that you can see makes a ranged spell attack against an ally with 30 feet of you, you can use your reaction to spend a number of ki point equal to the spell's level to make a DC saving throw equal to 10 + spell level (cantrips count as a 1).  If you pass the saving throw you can redirect the spell attack to another target(including the spellcaster) within the spell's range originating from your ally or to an empty space where it dissipates.  If you choose redirect the spell at another creature make a spell attack roll using your wisdom modifier + your proficiency bonus.

Hijack Spell

Starting at 17th level you learn to fully seize enemy spells for your own use.  If a creature that you can see casts a spell in which you are in range of you can use your reaction to spend a number of ki points equal to the spell's level in an attempt to seize control of the spell.  When you do, both you and the spellcaster must make contested ability checks using your spellcasting ability modifier + your proficiency bonus + any special modifiers.  Whoever wins the contested ability check may direct the cast spell as they see fit.