Path of a Hundred Seals

Tales once spread of a child who was almost crushed by its own exponential muscle growth. That child grew to be a Man, and grew to be both feared and respected as the greatest brawler of his time. But they had never gotten to fight at full force, as their power had to be sealed to protect them. Such were the 100 Seals.
Many have strived since then to somehow recreate or develop the condition afflicting this man.

You have succeeded.

100 Seals

At 3rd level, your power and muscle mass skyrocket, thus you are sealed by the 100 seals just like the Progenitor.
Your rage however breaks through, granting you the following benefits while Raging:

• Your unarmed strikes deal 1d4 bludgeoning damage. At 6th level, they deal 1d6 damage. At 10th level, they deal 1d8 damage and you can add half of your proficiency bonus to the damage of your unarmed strikes. At 14th level, they deal 1d10 damage.
• After using the Attack Action, you can use a Bonus Action to try and grapple your opponent.

Midare Botan

At 6th level, the crushing strength of your bare hands while raging makes you extremely dangerous within close quarters.

While grappling a target, you can use an action to squeeze down on one of their extremities, quite possibly breaking them, however, this requires concentration - you can only ever break one limb per turn. Make an attack roll, if you hit, you deal 2d6 bludgeoning damage + your strength modifier (+ ½ your proficiency modifier at 10th level)
In addition, the creature has to make a constitution saving throw. The DC = 8 + Your Strength Modifier + Your Proficiency Bonus

If they succeed, nothing happens, if they fail, depending on the extremity you grabbed, one of the following effects occurs:

• Arm: They can no longer use that arm (use it to make somatic components, wield weapons or shields), in addition, they suffer a -1 penalty to their Strength score per arm broken.
• Leg: Their walking speed is halved. In addition, they suffer a -1 penalty to their Dexterity score per leg broken.
• Wing: Their flying speed is halved. If they have only one wing, or both wings are broken, they can no longer fly.

A sentient creature can fix their broken limb by making a medicine check. The DC equals 10 at first. If the limb is broken again, the DC increases by 2. If only one limb is broken, you may make the check for free at the end of your turn. If both limbs are broken, this costs an action.

You can use this feature a number of times equal to your Strength modifier. The number of times you can use this feature resets per long rest.

Broken Arms:
Variant: Should you engage in a player vs. player setting and crippling their arms would severely limit their ability to fight back (if they rely on two handed weapons, can't switch to their offhand, can't roll damage die for their unarmed strikes like kicks and headbutts, or the spell they desperately need to cast requires a somatic component etc.), then they may still use their arms, however, the penalty to their strength remains, and they suffer 1d4 necrotic damage for whenever they use a broken limb (each time they cast a spell with a somatic component or attack with a weapon held in their broken arm).
If both of their arms are broken and they use a two handed weapon, it counts as an attack with both arms, thus dealing 1d4 necrotic damage per arm.
This lasts until they fix their broken arm.

Unparalleled Vigor

At 10th level, your endurance reaches an all time high, granting the following effects while raging:

• At the start of each of your turns in combat, you regain hit points equal to your Constitution modifier (minimum of 1 hit point). You don’t gain this benefit if you have 0 hit points or if you have more than half of your hit points left.
• You have advantage on Constitution Saving Throws
• When you would be knocked prone, roll a d20. On a roll of 11 or higher, you do not fall prone.

Thrúd

At 14th level, you gain control over your muscle growth, allowing you to undo the 100 Seals

The benefits you gained at level 3 are now permanently active, you needn't be raging.

Your Rage grants you these additional benefits:

• Your Strength Score and its Ability Score Cap increase by 2.
• When you would be stunned or incapacitated while raging, roll a d20. On a roll of 11 or higher, you are not subject to the effect.
• Your size becomes one category larger (as if under the "Enlarge" effect of Enlarge/Reduce) and you gain Expertise in the Athletics skill.