Monsters exist all across the multiverse, as do the everyday heroes that defeat them to protect the weak. Heroes for fun, or "Soul Heroes", don't do it for the glory or the fame, they fight to protect the weak for the challenge. Finding a worthy foe and becoming more powerful is a great drive for a soul hero: the true power of a hero is that they can change themselves on their own.

Basic Techniques

Starting at 3rd level, whenever you spend a Ki point on one of your features, you gain the benefits of the Disengage action. 

Additionally at 3rd level, you can use your Action to perform one of the following techniques:

 - One Punch - Make an unarmed strike against a creature within range, rolling twice the normal damage dice for the attack. On a hit, you can expend Ki points up to a number equal to half your level (rounded up). The target takes additional damage from the attack equal to 1d8 + your Dexterity modifier for each Ki point expended.

 - Normal Consecutive Punches - You expend two or more Ki points to perform a flurry of attacks, to a maximum number of points equal to half your level (rounded up). Each creature in a 10-foot cone must make a Dexterity saving throw. A creature takes 3d8 bludgeoning damage, plus 1d8 additional bludgeoning damage for each Ki point spent beyond 2 points on a failed save, or half as much damage on a successful one.

 

100 Push-ups, 100 Sit-ups, 100 Squats, and 10KM Running, Every Day

At 6th level, your daily training regimen has elevated your body to superhuman levels. You gain the following benefits:

 - Enhanced Lung Capacity - You can hold your breath four times longer than normal.

 - Body Temperature Control - You ignore any ill effects of hot or cold environments.

 - Immeasurable Strength - Your carrying capacity is doubled. This also doubles your push, drag, and lift weights.

 

Serious Consecutive Side Hops

At 11th level, you can use your immeasurable speed to hop from side to side rapidly, allowing you to create a multitude of afterimages. As an Action, you expend 3 Ki points to create three illusory duplicates, granting you the effects of the Mirror Image spell.

 

Serious Punch

At 17th level, when using your One Punch feature you roll four times the normal damage dice for the attack instead of twice, and the damage gained per expended Ki point is increased to 1d10 + your Dexterity modifier. Additionally, you no longer have a maximum number of Ki you can expend for the ability.