The Way of the Iron Wall emphasizes use of the shield, contrary to 5e requirements of not using a shield as a monk. This subclass is designed to make a more defensive monk who focuses on acting as a tank, with some ability to dish out additional damage (though not as much as other monk subclasses, at least that is the goal). The main offensive component is  the Shield Rebound ability unlocked at sixth level, which would require high Ki point usage and strategy to hit the same target more than once. At 17th level, when the shield rebound gains the ability to stun, this would further increase Ki-point cost at the trade off of stunning more than one target with a single attack action. The defensive aspects are meant to emphasize working with your party in close proximity so that they also can gain the benefits of the subclass features. Please leave comments on how you think this subclass could be improved - it is not playtested!

Iron Wall Technique

Starting when you choose this tradition at third level, you can:

• Equip a shield and attain the bonuses for doing so without negating the effects of unarmored defense and unarmored movement.
• Use your shield as a monk weapon. Its damage equals that of your martial arts die.

Protect Others

Starting when you choose this tradition at third level, your oath to protect others fuels your Ki energy.

• When you take the dodge action on your turn or when you use Patient defense, any ally within five feet of you also gains the benefits of the dodge action.
• As a reaction, when any ally within five feet of you is hit by a ranged attack, and you have space between to move between your ally and the attacker, you can move between your ally and the attacker to use your Deflect Missiles reaction.

Shield Rebound

Starting at sixth level, you can use your shield as a ranged weapon attack against those who would seek to do harm to you and others. Your shield gains the light and thrown properties, has a range of 60/120 feet, does damage equal to your martial arts die, and returns to you after hitting your target. You can use a Ki point to rebound your shield after it hits your first target to hit another target, but you must make another attack roll to hit the second target. You cannot hit the same target twice in a row. The shield can change directions after hitting the first target; however, the range is shared between targets. So if the shield travels 20 feet to hit one target, it only has 40 feet to hit a second target. After the shield has travelled 60 feet, any additional attacks made will be at disadvantage up to 120 feet. The shield returns to you after your final attack roll or if it has travelled 120 feet. You can rebound your shield as many times as your Ki points and shield range will allow.

Ki-empowered Shield

Starting at sixth level, your shield now counts as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

Ki-Fortification

Starting at eleventh level, you can use your Ki to further embolden your defence. As a reaction, you can use Ki points to increase your AC until the start of your next turn. Each Ki point you use adds to your AC, and you can use as many Ki points as you choose. Any ally within 5 feet of you also gains the benefits of Ki-Fortification until the start of your next turn.

Shield Stun

Starting at 17 level, your shield rebound is capable of rendering your enemies stunned. When you hit a creature using your shield rebound, you can spend a Ki point to attempt to stun the target. The target must succeed on a Constitution saving throw or be stunned until the end of your next turn. You can do this for each creature you hit with a shield rebound.