Muscular Puncher

Muscular punchers are a class of adventurer.  They are based on the wizard.

But while wizards train their minds, a muscular puncher trains only their body.  After years of eldritch exercises, a muscular puncher's muscles become corded things of impossible geometry and strength.  Within their bodies, their muscles speak to each other through subtle contractions, and engrave sigils on their very bones.  What a "mundane" wizard does with voice and concentration, they do through movement.  Their exertions are physical incantations knitted through the fabric of spacetime.

But muscular punchers don't know any of this.  All they know is that they are in possession of secret exercise manuals, which detail types of push-ups that man was not meant to know.  By performing these long exercise rituals, they store the power in their bodies, exactly like winding up the clockwork inside a toy.  And by punching, they release it.

Some muscular punchers come from secret gymnasiums.  Others come from circuses, where they are bred like animals and forced to learn the punches of their ancestors.  Many of them travel to learn to the nine forbidden punches, which combine to form the Apocalypse Combo, which can doom the world, or save it.

They have little patience for nerds, and don't believe that they have anything in common with wizards.

Loincloth HP

+3 maximum HP per hit die as long as you are unarmored.  Magical effects that would normally improve your AC instead improve your maximum HP, if they function at all.

Muscular Punch

At their option, their punches can either function as a dagger (1d6 damage) or a mace (1d6+Str damage).  Yes, this allows them to cut ropes by punching them.

Punches Per Day

Muscular Punchers can store punches inside their body in pretty much the same way that wizards store spells inside their head.  Use whatever chart or system you want for that, except use Con instead of Int.  I've written some level 1 punches at the end of this post, but if you want level 2+ punches, you'll have to either adapt some wizard spells or write your own.  When writing punches for this class, try to limit yourself to effects that could be appropriately delivered through a punch (no ranged attacks) or things that a person could conceivably do with magic muscles inside their body.  Muscular punchers always shout the names of their punches as they are performed.

Learning New Punches

A muscular puncher begins play knowing two level 1 punches, chosen randomly.  A muscular puncher can learn new punches from eldritch exercise manuals, other muscular punchers, or certain locations (like weight rooms dedicated to Nyarlathotep).  If they eat two scrolls containing level 1 spells, they will learn a previously-unknown level 1 punch (determined randomly).

Magic Punches

At level 3, a muscular puncher's punches count as magic, and they can punch ghosts and other incorporeal things.  

Level 1 Punches

Most of these punches are modifications to a basic melee attack.  For example, if a muscular puncher finds him- or herself in a dungeon without any doors, they can still use the Door Destroyer to get +2 to hit on a single attack (with no additional effect).

1. Atomic Butt Drop
2. Door Destroyer
3. Dragon Uppercut
4. Elbow Drop
5. Flying Clothesline
6. Haymaker
7. Saturday Night Punch
8. Nerd Slapper
9. Tag Team
10. Three-Point Landing

Atomic Butt Drop

+2 to hit and double damage.  Only usable against prone opponents.

Door Destroyer

+2 to hit.  As shatter or knock.

Dragon Punch

+2 to hit, double damage.  Can only be used against flying targets not higher than 30' off the ground.  This punch can also be used to jump 30' vertically.

Elbow Drop

+2 to hit.  Can only be used against targets at least 10' below you.  On a hit, the target takes all of your fall damage (in addition to normal punch damage), while you take none.

Flying Clothesline

As jump.  If you make a punch attack at the end of this movement against an opponent who is at least 30' away, you get +2 to hit and the struck opponent must make a Str check or be knocked prone.

Haymaker

-2 to hit, triple damage.

Saturday Night Punch  

+2 to hit, If target fails a save, their clothing/armor is destroyed.

Nerd Slapper

+2 to hit.  The target takes an additional +2 damage for every spell it is capable of casting.  (Wizards who have expended all of their spells take no additional damage.)

Tag Team

You and a willing ally (who has not yet acted in this turn) make simultaneous melee attacks against a single opponent.  You both get +2 to hit.  If both attacks hit, the target takes an additional +1d6 damage.

Three-Point Landing

As feather fall, except there is no reduction of fall speed.

The first person to write up a muscle wizard was Ian over at the now-defunct Monstrous Television.  Others have proposed excellent alternatives.  I suppose other influences would have to be professional wrestling, Flex Mentallo, and those kung fu manuals (a la Kung Fu Hustle).