Hello.
I've stumbled upon this thread today and checked it thoroughly. From my limited and subjective view, this is a great implementation and I can't wait to try it out.
What could I add to this...
Martial arts styles as an optional addition? Along the lines of the ones listed in OA.
Or something like this.
A few additional feats could help the class too.
Here are some that looked fitting:
There is a trio of similar skills, one of which was listed by you - Flying Kick.
As others had pointed out, double the damage seems somewhat overpowered, maybe it could be modified and/or mixed together with the following:
Battle Jump
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You know how to launch a devastating attack from above by dropping onto your opponent.
Benefit: You can execute a charge by simply dropping from a height of at least 5 feet above your opponent. For example, a ledge 10 feet above the floor of a cavern would suffice for jumping on a Medium-sized creature, while a ledge 15 feet high is required for a jumping on a Large creature. You can't jump from more than 30 feet above your opponent, nor can you effectively battle jump while under the influence of a fly or levitate spell or effect, as you have to hurl yourself down on your foe.
If you hit, you can choose either to deal double damage with a melee weapon or natural attack or to attempt a trip attack. You are treated as one size category larger than normal if you try to trip your opponent with the battle jump. After you attack, you take falling damage as normal for the distance you jumped. You are entitled to a Jump check (DC 15) to take less damage, as if you had fallen 10 feet less than you actually did. If you fail this Jump check, you fall prone 5 feet from your opponent.
You can also use Battle Jump to begin a grapple attempt instead of making a normal attack. If you do, you are treated as one size category larger than normal for the first grapple check following the battle jump.
Normal: Anybody can try to jump down on an enemy, but it is not considered a charge, and they do not gain double damage or the size bonus for the ensuing attack.
Leap Attack
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You can combine a powerful charge and a mighty leap into one devastating attack.
Prerequisite: Jump 8 ranks, Power Attack.
Benefit: You can combine a jump with a charge against an opponent. If you cover at least 10 feet of horizontal distance with your jump, and you end your jump in a square from which you threaten your target, you can double the extra damage dealt by your use of the Power Attack feat.
If you use this tactic with a two-handed weapon, you instead triple the extra damage from Power Attack.
This attack must follow all the normal rules for using the Jump skill and for making a charge, except that you ignore rough terrain in any squares you jump over.
So, what if the modified feat only doubles the damage added by Power Attack usage? Together with a two-handed fighting style (hammer fist) it would be multiplied by 3.
Plus keep the option of exchanging the extra damage in favor of trip attack (like in Battle Jump).
Call it something like Mantis Leap.
Hammer Fist
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You are trained in an unarmed fighting style that emphasizes two-handed strike.
Prerequisite: Str 13, Improved Unarmed Strike
Benefit: You may make a single unarmed attack with both hands to add 1-1/2 your Strength bonus on the damage roll. This extra damage does not
apply if you make a flurry of blows attack or you are holding anything in either hand.
Snap Kick
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You have continued to hone your unarmed combat skills, and you deal more damage with your unarmed strikes.
Prerequisite: Improved Unarmed Strike, base attack bonus +6.
Benefit: When you make a melee attack with one or more melee weapons (including a standard attack, full attack, or even a strike maneuver), you can make an additional attack at your highest attack bonus. This attack is an unarmed attack that deals damage equal to your base unarmed attack damage + 1/2 your Str bonus. You take a -2 penalty on all attack rolls you make this round.
Superior Unarmed Strike
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Your unarmed strikes have become increasingly deadly, enabling you to strike your foes in their most vulnerable areas.
Prerequisite: Improved Unarmed Strike, base attack bonus +3.
Benefit: You deal unarmed damage as a monk four levels higher.
Versatile Unarmed Strike
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You employ a variety of unarmed fighting styles, allowing you to alter the type of damage your attacks deal.
Prerequisite: Improved Unarmed Strike
Benefit: As a swift action, you can opt for your unarmed strikes to deal your choice of bludgeoning, piercing, or slashing damage. Once you make this choice, your unarmed strikes continue to deal the chosen damage type until you use another swift action to change it.
Acrobatic Strike
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Your dexterous maneuvers and skilled acrobatics allow you to slip past a foe's defenses and deliver an accurate strike against him.
Prerequisite: Tumble 12 ranks
Benefit: If you succeed in using Tumble to avoid an opponent's attack of opportunity, you gain a +4 bonus on the next attack that you make against that foe as long as the attack occurs before the end of your current turn.
Knock-Down
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Your mighty blows can knock foes off their feet.
Prerequisites: Base attack bonus +2, Improved Trip, Str 15+.
Benefit: Whenever you deal 10 or more points of damage to your opponent in melee, you may make a trip attack as a free action against the same target.
Errata-ed: Use of this feat cannot be combined with Improved Trip to generate an extra attack, and successful use of this feat does not grant an extra attack through the Cleave or Great Cleave feats.
Snatch Arrows
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You are adept at grabbing incoming arrows, as well as crossbow bolts, spears, and other projectile or thrown weapons.
Prerequisites: Base attack bonus +3, Deflect Arrows, Dex 15+, Improved Unarmed Strike.
Benefit: You must have at least one hand free (holding nothing) to use this feat. When using the Deflect Arrows feat, you may catch the weapon instead of just deflecting it. Thrown weapons such as spears or axes can be thrown back at the original attacker as an immediate free action or kept. Projectile weapons such as arrows or bolts can be fired back normally on your next turn or later, if you possess the proper kind of bow or crossbow.
Choke Hold
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You have learned the correct way to apply pressure to render an opponent unconscious.
Prerequisites: Improved Unarmed Strike, Improved Grapple, Stunning Fist.
Benefit: If you pin your opponent while grappling and maintain the pin for 1 full round, at the end of the round your opponent must make a Fortitude saving throw (DC 10 +1/2 your level + your Wisdom modifier). If the saving throw fails, your opponent falls unconscious for 1d3 rounds.
Defensive Strike
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You can turn a strong defense into a powerful offense.
Prerequisite: Int 13+, Expertise, Dex 13+, Dodge.
Benefit: If an opponent attacks you and misses while you are using the total defense action, you can attack that opponent on your next turn with a +4 bonus on your attack roll. You gain no bonus against an opponent that does not attack you or against an opponent that attacks and does not miss.
Defensive Throw
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You can use your opponent's weight, strength, and momentum against her, deflecting her attack and throwing her to the ground.
Prerequisite : Dex 13+, Improved Unarmed Strike, Dodge, Improved Trip, Combat Reflexes.
Benefit: If the opponent you have chosen to receive your AC bonus from the Dodge feat attacks you and misses, you can make an immediate improved trip attack against that opponent. This attempt counts against your allowed attacks of opportunity this round.
Falling Star Strike
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You have mastered the art of striking a nerve that blinds a humanoid opponent.
Prerequisites : Improved Unarmed Strike, base attack bonus +4 or higher, Stunning Fist, Wis 17+.
Benefit: Against a humanoid opponent, you can make an unarmed attack that has a chance of blinding your target. if your attack is successful, your target must attempt a Fortitude saving throw (DC 10 + 1/2 your level + your Wisdom modifier).
If the target fails this saving throw, he is blinded for 1 round per level you possess. In addition to the obvious effects, a blinded creature suffers a 50% miss chance in combat (all opponents have full concealment), loses any Dexterity bonus to AC, grants a +2 bonus on attackers' attack rolls (they are effectively invisible), moves at half speed, and suffers a -4 penalty on most Strength- and Dexterity-based skills.
Should most likely count as 1 usage of stunning fist.
Grappling Block
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You can catch and pin an opponent's weapon with your bare hands.
Prerequisite : Improved Unarmed Strike, Deflect Arrows, Int 13+, Expertise, Improved Disarm, Combat Reflexes.
Benefit: You must have both hands free or be holding weapons designed to catch other weapons to use this feat. Once per round when you would normally be hit by a melee weapon, you may make a special disarm attempt against your opponent. This attempt counts against your allowed attacks of opportunity this round. You make an opposed attack roll (with your unarmed strike, sai, or jitte) against the attack roll that hit you. The opponent's attack roll is not modified by the size of the weapon. If you succeed, you grab the weapon away from your opponent (if you are unarmed) or knock the weapon to the ground (if you are armed). You may only use this feat against weapons up to two sizes larger than you.
Deflect Arrows requirement seems excessive here.
Prone Attack
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You attack from a prone position without penalty.
Prerequisites: Base attack bonus +2 or higher, Dex 15+, Lightning Reflexes.
Benefit: You can make an attack from the prone position and suffer no penalty on your attack roll. If your attack roll is successful, you may regain your feet immediately as a free action. Opponents gain no bonus on melee attacks against you while you are prone.
Unbalancing Strike
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You can strike a humanoid opponent's joints to knock your target off balance.
Prerequisites: Improved Unarmed Strike, Stunning Fist, Wis 15+.
Benefit: Against a humanoid opponent, you can make an unarmed attack that has a chance of unbalancing your target, if your attack is successful, you deal normal damage and your target must attempt a Reflex saving throw (DC 10 + 1/2 your level + your Wisdom modifier). If the target fails this saving throw, he is thrown off balance for 1 round, losing any Dexterity bonus to AC and giving attackers a +2 bonus on their attack rolls.
Also as 1 stunning fist attack?
Deft Opportunist
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You refuse to give into death while your comrades still depend on you.
Prerequisites: Combat Reflexes, Dex 15
Benefit: If you begin your turn adjacent to a foe who did not attack you in the last round, you may immediately make an attack of opportunity against that foe.
Elusive target
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Trying to land a blow against you can be a maddening experience.
Prerequisite: Dodge, Mobility, base attack bonus +6
Benefit: The Elusive Target feat enables the use of three tactical maneuvers. Negate Power Attack: To use this maneuver, you must designate a specific foe to be affected by your Dodge feat. If that foe uses the Power Attack feat against you, the foe gains no bonus on the damage roll but still takes the corresponding penalty on the attack roll. Diverting Defense: To use this maneuver, you must be flanked and you must designate one of the flanking attackers to be affected by your Dodge feat. The first attack of the round from the designated attacker automatically misses you and may strike the other flanking foe instead; the attacking creature makes an attack roll normally, and its ally is considered flatfooted. If the designated attacker is making a full attack against you, its second and subsequent attacks function normally. Cause Overreach: To use this maneuver, you must provoke an attack of opportunity from a foe by moving out of a threatened square. If the foe misses you, you can make a free trip attempt against this foe, and the foe does not get a chance to trip you if your attempt fails.
Deadly Defense
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You are at your most dangerous when forced to protect yourself.
Benefit: When fighting defensively, you deal an extra 1d6 points of damage with any light weapon or with any weapon to which the Weapon
Finesse feat applies (such as a rapier, spiked chain, or whip).
This feat’s benefit applies only when you are unarmored or wearing light armor and not using a shield.
Special: If you have the Combat Expertise feat, you also gain the benefit of Deadly Defense when taking a penalty of at least –2 on your attack roll from that feat.
Melee Evasion
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Your speed, agility, and talent for intelligent fighting allow you to avoid your opponent's blows. You take careful stock of an opponent and slip away from his sword blow just as he commits to the attack.
Prerequisite: Combat Expertise, Dodge, DEX 13, INT 13
Benefit: While fighting defensively, you can attempt to negate a single attack made by the target of your Dodge feat. If this opponent attacks you, use an immediate action to make a d20 roll modifi ed by your highest base attack bonus. The result is used as your normal AC and touch AC against that single, specifi c attack from your opponent. You cannot use this feat if your Dexterity bonus to AC does not apply against your opponent's attack.
Feign Weakness
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You capitalize on your foe’s perceptions of your unarmed status.
Prerequisites: Base attack bonus +2, Improved Unarmed Strike.
Benefit: If you make a successful Bluff check against your opponent’s Sense Motive check, you lure the foe into attempting an attack of opportunity because he thinks you are unarmed. But you are armed, and you make your attack against your drawnout foe who is caught flat-footed, before he takes his attack of opportunity.
You also may attempt this feat with a Tiny or Small weapon with which you are proficient by attempting to hide it until the last second, but you incur a –2 or –6 penalty on your Bluff check, respectively. You can use this feat with a disguised weapon, such as a war fan, at no penalty on the Bluff check.
Errata-ed: Using Feign Weakness is a standard action, just like a feint, except that if you succeed you get to make your attack immediately. You can only Feign Weakness once per encounter. After one use, your opponents are too wary to fall for this maneuver again.
Pulverize foe
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You enjoy smashing your opponents into submission.
Prerequisites: Str 15, base attack bonus +6, proficient with bludgeoning melee weapon.
Benefit: If you hit the same enemy more than once in a single round with a bludgeoning melee weapon, you deal an extra 1d6 points of bludgeoning damage with each hit after the first.
The alternative class feature from Dungeonscape seems nicely fitting too.
Alternative Class Feature: Wall Walker
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You have the uncanny ability to travel along vertical surfaces for a short time.
Level: 4th.
Replaces: If you select this alternative class feature, you do not gain the slow fall ability.
Benefit: Beginning at 4th level, as a move action, you can run up or down a vertical surface a total distance of 20 feet without making a Climb check. You add 10 feet to this distance at 6th level and every two levels thereafter, up to your maximum speed. You can use this ability only once per round (so you can’t make a double move up or down a wall).
If you do not reach the top of the vertical surface or find a suitable hand- or foothold, you must make a Climb check appropriate to the surface. If you succeed on the check, you can use this ability again in the next round.
Otherwise, you fall or make no progress, as determined by the check result.
You can’t use this ability to traverse a ceiling or overhang.
Aaand another one:
Prayerful Meditation
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Your religious convictions protect you from the spells and
magical abilities of those who oppose your beliefs.
Level: 3rd.
Replaces: This benefit replaces the still mind class
feature.
Benefit: Your adherence to a religious path has developed
in you a resistance to antithetical magic. You gain a +2 bonus
on saving throws against spells and effects from chaotic-
aligned creatures and creatures with a moral (good/evil)
alignment component opposite to yours. This is a super*
natural ability.
Edit: Also, there was something that added Wis modifier to the number of AoO, but I can't find it now.
And something about the hands that can make them deal any of the 3 damage types: slashing, bludgeoning or piercing.
May I suggest making the innate speed bonus the monks have stack with enhancement speed bonus somehow?