Way of the Iron soul

The Order of Iron soul focuses on training one's body and soul. Those following the path of Iron must pace themselves, or have their body and mind broken. The training of Iron soul is notorious for its brutality. Those who reach the rank of Ironmaster are revered. Most who follow the iron path is content with the amount of training they can manage, and accept their limits. 

As part of the Iron soul, you focus on improving yourself and finding ways to expose your enemies.

Path of Iron.

Starting at 3rd level, your willpower has been hardened like tempered Iron. When you spend  Ki point to flurry of blows, step of the wind, or patient defense, you gain 5 temporary hit points.

These temporary hitpoints increase at level 6 (10), 11 (15), 17 (20).

Focused reflex.

starting at 6th level, your trials have led you to develop further. Your reflexes have become quicker than lightning. You gain Additional reaction = to your wisdom modifier.

 

Additionally, you know how to harness the energy within elements. Although you may not be able to manipulate mountains or seas, you can more easily deflect them. When you use deflect missile you can expend additional reactions to add another D10 to the roll. For example, if a large stone is thrown at you, you may expend 2 of your reactions to roll 2D10+monk level+ dexterity modifier. With this ability you can also return much larger projectiles (Such as boulders thrown by giants) if you successfully deflect.

Reveal weakness

Starting at 11th level, your mind is becoming more focused. You can see a unique weakness' in your foes' spiritual body. And now you know how to properly strike it. But you may also use this new knowledge to assist allies. 

When you hit a creature with your flurry of blows you may apply reveal weakness. For the next minute, when the marked creature is hit by an attack, you may use your reaction to give the marked target vulnerability to the damage. You can mark a number of targets = to your wisdom modifier.

Additionally, you can predict the subtle changes in the air. While you have temporary hit points, you have advantage on all saving throws.

Iron body technique

Starting at 17th You have learned a sacred technique among monks of the Iron soul. You can focus your ki into your skin to harden it like iron. With your mastery of this technique, you are not slowed by this technique, and your fists fly faster. 

At the start of combat, or as an action on your turn, you may expend 5 ki points to gain resistance to all damage for 1 minute. While this effect is active, you also attack 4 times with flurry of blows instead of two. You also gain an additional die of martial damage while this effect is active.