Way of the Iron Body
Monks of the Iron Body focus on strengthening their muscles, not for power, but for defense. They can harden any part of their body at will, in order to block attacks and retaliate with powerful blows of their own.
Block and Counter
When you choose this tradition at 3rd level, you gain the ability to further protect yourself from attacks, as well as retaliate against you foes.
When you take the Dodge action on your turn, you gain a bonus to your AC equal to your proficiency bonus. Furthermore, when an enemy within 5 feet of you misses an attack against you while you are Dodging, you can spend 2 ki points to use your reaction to make an unarmed strike, or an attack with a monk weapon, with a bonus to the damage roll equal to your wisdom modifier.
Iron Muscles
Also at 3rd level, you can add your Wisdom modifier to any Strength skill check or Strength saving throw you make.
Unpiercable Shield
You focus and hone your skills, learning to shield your allies from attacks, not just yourself.
At 6th level, when an ally within 5 feet of you is targeted with an attack, you can use your reaction to cause the attack to target you instead. If you do so, you can use your Deflect Missiles feature on it if it is a ranged attack, or respond with a counter if it is a melee attack and the attacker is within 5 feet of you.
Interception
You have tightened your defense, both of yourself and others, and ensure that nothing gets past you.
Beginning 11th level, if you have not moved during your turn, the range for your Unpiercable Shield ability equals half of your movement speed. If the triggering attack is more than 5 feet away, you must move up to half your movement speed, ending within 5 feet of the trigger.
Furthermore, when you use your reaction to use your Deflect Missiles feature, you can spend a ki point, and use this feature an unlimited number of times without using a reaction, until the start of your next turn.
Unparalleled Defense
At 17th level, you have become so adept at strengthening your body that it has become instinctive.
You gain resistance to the first attack that hits you on your turn that deals bludgeoning, piercing, or slashing damage. Furthermore, when when you take bludgeoning, piercing, or slashing damage, you can spend 2 ki points to reduce that damage by 1d10 + your Dexterity Modifier + your monk level.