Way of the Arcane Stalker

Monks of the Way of the Arcane Stalker  have spent years honing their skills to counteract magic.  They learn techniques to detect, protect, and interfere with the flow magic via the manipulation of ki.

Nimble Mind

Starting when you choose this tradition at 3rd level, whenever the Monk is targeted by any spells they may substitute their Dexterity modifiers with their Intelligence modifiers for Deflect Missiles in an attempt to deflect the spell.

Additionally, when taking this tradition gain proficiency in Intelligence (Arcana) if you do not already have it.

Interrupt Magic

Your years studying arcane practitioners allows you to interfere with their manipulation of magic. At 6th level, when a creature within 5 feet of you casts a spell, you can use your reaction to make an Intelligence (Arcana) check against the target's spell save DC.  On a success the spell is not cast, spell slots are consumed along with any components specified as consumed in the spell description.

Arcane Resistance

Starting at 11th level you hone your defense against magic.  Gain resistance to all magic damage, regardless of type.  This resistance does not stack with resistances gained from other sources.

Block the Flow

Your mastery of tracking the flow of magic allows you to interrupt its flow for a protracted period of time.  After 17th level, once per round, upon successfully striking a target with an attack action, you can spend a ki to block the target's ability to cast spells from one school of magic.  The block lasts until the end of a short or long rest.