Is this Way of The Iron Fist homebrew monk subclass too overpowered?

Question

This homebrew subclass is something I came up with to compensate for the fact that my group has only three members, and I as a monk am the only one remotely capable of tanking.

I call it the Way of the Iron Fist:

Way of the Iron Fist

You are a monk who has forged yourself into a weapon after years of brutal training and hardship to atone for a past evil and fight as a defender of the common people.

Iron Fists

At third level when you assume this tradition, your fists and feet become as hard as iron from years of brutal training in martial arts. This grants you the ability to deal 3 extra damage on unarmed strikes. Your fists also have the ability to strike the ki of the creature that you are striking, allowing you to siphon their ki and regain up to 3 HP per melee attack if you are striking an enemy while injured.

Iron Defense

At third level, due to the iron strength of your limbs, you are capable of blocking melee weapons with your hands. If a melee attack hits you, you can choose as a reaction to make a Dexterity saving throw against your ki save DC; if you succeed on the saving throw, you can, as a last ditch defense, catch the melee weapon with your hands to deflect the blow.

Iron Heart

At sixth level, you can have an extra strike added to Flurry of Blows.

Iron Will

Upon reaching 11th level, your will has become as strong as iron from brutal mental conditioning and transcending your fears to resist those who attempt to control your mind. You cannot be charmed, frightened, or put to sleep. You also gain resistance to psychic damage, and creatures cannot see your thoughts or intentions due to your strength of mind.

Iron Body

After years of self-imposed hardship to toughen your body, your entire body has become as strong as iron. You no longer feel pain and cannot be incapacitated by physical blows, and gain resistance to bludgeoning, slashing, and piercing damage.

I really love this subclass idea as it fits perfectly with my character's backstory, but I am afraid it would make them way too overpowered and unbalance the game.

Is there any way maybe I should change it to make it less overpowered if it is too strong?

Answer 1

This subclass is overpowered

Before I get into balance, there are a few things that don't mesh well with current mechanical standards, such as the way you use your ki save DC.

Level 3 - Stronger than established options

(ignoring ability modifiers because they should be uniform throughout)

Level three usually gives the monk more versatility, rather than a damage boost. The closest we have is the Kensei, allowing the use of a longbow. A longbow is 4.5 damage (1d8) and the Kensei's Shot ability lets you add 2.5 (1d4) at the cost of a bonus action, bringing the total up to 7 damage for 1-2 attacks. Comparatively, your iron fist is dealing 5.5 damage on every attack, including the bonus action punch (or Flurry of Blows).

This is a sizable boost from using a quarterstaff for your Attack Action (4.5 or 1d8) and then standard unarmed (2.5 or 1d4).

And in addition to that, you have this Iron Defense thing that is really hard to read, but looks like you're basically just going for a melee version of Deflect Missiles. If this feature were just a melee version of Deflect Missiles, then it might actually be a balanced feature, but as-is, you're basically granting a 60%+ chance to nullify one attack per turn. (d20+PROF+DEX vs 8+PROF+WIS is at worst, going to be equivalent to d20 vs 8)

Level 6 - Stronger than established options

Iron Heart is again using this odd ki save dc notation, but it probably equals out to around 13 at this level (Eventually increasing to a maximum of 19). Compared to the Open Hand Monk's Wholeness of Body feature (three times your monk level once per long rest), Iron Heart is definitely stronger. Iron Hear can be used several times between rests and even resets on a short rest. It does take up your action, so I'm not sure how much stronger it is than Wholeness of Body, but it's an amount stronger. I would just directly copy Wholeness of Body and use that.

Level 11 - Unclear, but likely stronger than established options

Iron Will is another weird one. It's unclear what "cannot see your thoughts or intentions" means. And making yourself always immune to charm, fear, and sleep is very strong (and also negates the Monk 7th level feature Stillness of Mind).

It looks like took the 8th level spell (15th level wizards) Mind Blank and made it permanent.

The closest comparison is Tranquility from Way of the Open Hand and that ends if you attack and still allows a save to get through.

Level 17 - Unsure, likely weaker than established options

This tier is usually "an extra attack" or "an extra way to do damage", so it's off convention, for sure. While plenty of damage coming in at level 17 falls under B,P,S the scary stuff (like being eaten by a Tarrasque, or melted by a Death Tyrant) isn't, so I don't know how much mileage this is going to get.

However, I want to make sure that "You no longer feel pain and cannot be incapacitated by physical blows" has no actual mechanical side effects, such as "You cannot be reduced to 0 hp by bludgeoning, piercing, or slashing damage", which would push this over the line to definitely being overpowered.