Born without the ability to use magic, many people don't have the luxury to flick their wrists and call spells to their defense. Some magic user put this power to good, some bad. Those without magical abilities had to learn how to protect themselves against the mages that so easily threaten them. This is how Ki Blockers came to be. By studying the pressure points in the body where ki flows through they are able to weaken and stop mystics before they can unleash their frightening powers

Light on Your Feet

You gain proficiency in the acrobatics ability if you didn't already have it. If you succeed on a dexterity saving effect against a magical ability or effect you may immediately move up to 10ft as a reaction. If this would take you out of the triggering AOE, you ignore all damage, and if it brings you within melee attack range of the caster/creator of the triggering effect you may make an unarmed strike against them. Concentration checks provoked by this reaction have disadvantage. 

Restricted Flow

When you use your flurry of blows and land both attacks against a creature with magical abilities (innate or learnt), you disrupt the flow of magic within them. Any magical ability or spell that they attempt to use before the start of your next turn causes them to take your Wisdom modifier+proficiency bonus as necrotic damage. They must then make a constitution saving throw against your Monk Spell Save DC, on a fail they are unable to perform a magical ability or spell until the start of your next turn, though may still make sure of their full turn. 

Death by a Thousand Fists

You’ve become adept at finding your enemy’s pressure points the more that you attack them. For every consecutive attack roll that you make with an unarmed strike against the same target, you lower the natural roll that you need to make to get a critical hit. For example, if you have hit the same creature with three consecutive unarmed strikes you can crit on an 18, 19 or 20. This resets back to 20 if you attack a different target, use a weapon to attack or score a critical hit. Additionally, you add your Wisdom Mod to damage as well as your Dexterity Mod to calculate damage when you get a critical hit.

Redirecting Flow

The Light on Your Feet feature now has a reaction movement speed of 30ft and may be used against any spell or magical effect that forces you to make a Dexterity, Strength or Constitution saving throw. On a success you may now also absorb the magical energy of the effect to restore Ki points. You replenish a number of Ki equal to the spell level if a spell, or 3 if an innate magical effect. If you restore Ki this way, the next flurry of blows that you use before the end of your next turn does an extra 1d10 of the spell's damage type on each strike.