Level 12 Analysis

Your AC is very low. At level 12, AC 18 is essentially a death sentence. I'm going to assume you have a source of Mage Armour from a party spellcaster, giving you an AC of 22, and a further Ring of Protection or Amulet of Natural Armour or Barkskin or something to up that by +2 to 24. 24 AC is still incredibly low.

The lowest attack bonus I found with a quick peruse of CR 12 monsters is +18, the secondary Bite of an Athach. That hits you on a roll of 6. The most common number I found was +23, which would hit you on a 2. I saw lots of +26, +28 and even a +33. Those all hit you on everything but a natural 1.

In other words, your AC is too low if anything targets you for you to survive. The DM will have to pull punches not to kill you.

Valiant Stand improves this. By not by enough. Enemies are still going to autohit you. Best case is +4 stat boosters on dex and wis, mage armour, nat armour/deflection bonuses, and valiant stand - 18 base, +4 from enhancement to stats, +4 armour, +2-+3 nat armour/def, +3 valiant stand = 32. That's a hit on a 9 from the lowest common attack bonus I found on CR 12 monsters.

Your Attack Bonus Is Pretty Decent, For a Monk. You have +16 to hit without Smite. With Amulet of Mighty Fists +2, that's +18ish to hit. With Belt of giant Strength +4 or Bull's Strength, that's +20 to hit. Everything that has AC that is supposed to be a defense has 26+, which is good - you hit most of the time. Power Attack and Flurry are counterbalanced by Valiant Stand, which you should be endeavouring to have always active by use of Stealth, which you don't have maxed out, uh, why? Popping up out of nowhere for a flatfooted smiting power attacking flurry should be your opening round action in every combat. Even your iteratives have a decent chance to hit, with this hit bonus. Only decent, though.

Your Damage Isn't Great. 1d10+1d4+5 (where is that errant +1 damage coming from?) averages out to 13 points of damage per strike. With Power Attack, that's 19 damage. With Smite, against evil or chaotic outsiders/dragons, you get /+18/, so 34 damage per strike, which is actually level 12-worthy. Too bad you get 3 total attacks per day with that damage. Sweeping Smite carries the Cha-to-hit bonus, but not the damage from the 'first hit'. It's kind of like a really terrible whirlwind attack that way.

Most of the time you'll be attacking for 19, on average. Some stuff is immune to bleed, or has DR/cold iron and good, etc, so it might be less. If you move, you only have one attack, so your first round barring stealth will nearly always be one attack at best. Rounds after that, you can flurry for four attacks, each which might hit for 19 damage.

So a max damage on an ideal round of around 34+19+19+19 damage, or 91 damage in 4 hits. That's not terrible. It relies on getting a full round action, though. It also relies on hitting with iteratives, DR of the kind you can get past, no miss chances etc. Most monsters at this level have at least 150hp, so you won't be winning in hp races. But you will be able to contribute a bit at least to the usual team of four on one beatdowns.

Your HP gets eaten in a round. With your AC, most CR9+ melee monsters are going to kill you to dead in a round. 11 Constitution on a melee combatant isn't a great idea, but then, you're a monk and need wis and and dex and str and also cha for being a paladin, so eh.

Your Saves are decent. They could be better, but they could also be worse. Most DCs seem to hover around DC 23 at this level, going up as high as 28 but also as low as 21. With your +11/+11/+13, you should have a 50% shot at most saving throws, and although fear and poison aren't exactly the most common life-threatening things to save against, it's still nice.

Power Level: Fighter.

This character can be relied upon to be roughly as good as an unoptimized fighter. The DM will have to pull some punches, and tough encounters (CR +2 or greater) will have a good chance of one-shotting this character by accident. In a party with Rogue or better power levels, this character will feel notably weaker than the rest of the group.

Note

Evaluating something without gear is hard, because at the lower end of the scale, gear can have more effect on your ultimate spread of numbers than the classes chosen. If your gear is random stuff, you will be weaker. If you plug it all into boosters for your FOUR necessary stats (dex, wis, str, cha), rings of deflection and other stuff that helps boost your melee stats to make you 'great' at that rather than 'mediocre to good', which includes buffs from friendly spellcasters, you will be stronger.

Note

This build is stronger at lower levels, where a handy Mage Armour plus your defensive stats can put you out of reach of opponents attack bonuses, and things are easier to hit and easier to kill. Level 12 is definitely where things are starting to go 'downhill', and they will likely get worse as enemy AC and AB increase and every enemy has flying or spells and abilities.

Note

The build has no movement capability other than skills-based climbing, swimming, jumping. I'm assuming again allied spellcasters will be patching that hole with buffs, especially since with the other gear i've assumed in your build you don't have the money to buy gear to get flight or teleport or whatnot.

Suggestions

Your main problem is that you're playing a monk. Without serious optimization, monks are very weak. You've done a bit of optimization here, and pushed it up to unoptimized fighter level, but fighter is still not great if you're planning to be in a party with casters. Or if you're fighting caster-style enemies like many demons are.

Most of the tricks I know to make melee characters more competitive are in 3.5e. I'm assuming there's no backward compatibility in your group. So that's all out the window.

Paladin isn't giving you much other than flavour, either. You've got a decent Flurry and Attack Bonus, but you're way too fragile to make good use of it, unless your enemies come in the 'always attack the guy using the full defense action with the tower shield' variety.

In this case, i'd recommend Summoner. Synthesist Summoner. It slices, it dices, it buffs, it has level appropriate abilities, natural attacks, the works. It is, in fact, so good that you could mix it with a Paladin dip and still be relatively awesome.

Evangelist lets you keep advancing as a Summoner while also adding a divine feel to the class. It's also the only prestige I can find that advances your eidolon aka living armour, so.

Other. than. that... there's a good rogue-based fear build, but I don't know how relevant that is to your concept.

I feel like there's some way, between Fighter archetypes and the Hungry Ghost Monk monk archetype, to create kama-wielder who reaps ki from his opponents and uses it to chain-stun them with a huge Wisdom and Dex, just whittles them away with flurries of weak, ki-reaping attacks and then spends the ki on stuns. There's too many damned archetypes though.

Even if you're taking summoner, it's kind of worth dipping monk as well. You have to be unarmoured to use your synthesism, so you could benefit from a high wisdom score to your AC. Not worth going Hungry Ghost, because the ki-drain only comes at level 5. Just a one, or at max 2-level dip. Probably after you have 1 or 3 levels of synth summoner.

Yeah I cannot find anything that is about punching people that isn't just a Fighter or Barbarian with a 2-hander sword that is any good. There's some rogue stuff that is nice, there's an alchemist archetype that gets sneak attack and would make a murderously effective hand to hand combatant with the mutagen and the buffs. But nothing based around jumping on things and punching people except synth summoner. Yeah. That's my advice.

Synthesist Summoner 20.

Optional; Monk 1.

Optional; Evangelist.

First, it must be said: monk is a weak class. The best number of monk levels you can have is zero, and unarmed swordsage would be literally strictly-superior. I am assuming, per the question, that the first two monk levels are set in stone, but if they are not, I would strongly consider alternatives.

For a quick run-down...

Monk 1 is a fairly solid level

You get two bonus feats (Improved Unarmed Strike and one other), great saves, and Wis-to-AC. The HP, BAB, skills, and proficiencies are all mediocre, but oh well, they’re not exactly atrocious either. Flurry of Blows... well, it’s optional, so you can always opt to not use it.

Two bonus feats in one level is worth a fair bit, so cool.

Monk 2 is... OK enough

Evasion is pretty good, another level of all-good saves is solid, and hey, yet another bonus feat. You can do better but it’s not awful. If you aren’t using sane multiclassing rules for BAB (read: fractional), the BAB’s also as good as you’re gonna get. So yay.

Monk 3 and 4 are just bad

Still Mind is a small bonus to saves against only a single school of magic. It doesn’t even cover all mind-affecting things. There’s a reasonably good chance that you will forget you have this bonus when the time comes to roll a save it works on.

Fast Movement is a little better; you’ll probably remember you have it, anyway. But it’s still not great; it is not something that’s going to be particularly relevant most days, since you typically want to stay with your party and rarely are going to need more than 30 but less than 45 feet of movement in combat.

Ki Strike is OK enough, except you need magic bonuses to your unarmed strikes anyway. So you are going to have an item that obviates this class feature. The better option is necklace of natural attacks^SS; a +1 amulet of mighty fists is ridiculously overpriced, but will cover your need for magic damage.

Slow Fall is just insulting.

The unarmed strike damage improvement works out to an average of +1 damage. You can do better.

Alternatives

So, what to take instead of those levels of monk?

Cleric

Cleric is almost-certainly the best single-level dip in the game. Won’t improve your HP or BAB, but it will give you fairly-good saves, and more importantly a couple of spells and the right to pick a couple of Domains. This is a big deal.

The best choice for you is to take the Travel Domain, and then swap it for Travel Devotion.^CC This just about instantly solves your mobility issues, as it allows swift-action movement for a whole minute each day, with additional minutes gained by burning Turn Undead uses. A Cha of 12 is sufficient to get 3 minutes of this every day. If you have low Charisma, or just want to make sure you always have enough Turn Undead uses, you could just take the Undeath Domain to get Extra Turning.

Other solid options include the fantastic Time Domain, for Improved Initiative, a solid feat in its own right that is also often required for things. Along those lines, the Darkness or Shadow Domains get Blind-Fight, which is kind of mediocre but is another common requirement. War gives Weapon Focus, and deities who favor unarmed strikes exist, but I would only do that if I were eyeing some things that require Weapon Focus, as the feat is quite poor.

For non-feat options, you could do a whole lot worse than the Magic Domain; a single level in cleric paired with the Magic Domain means you get to use every single cleric and sorcerer/wizard wand in the game, with no Use Magic Device check. That is really nice, particularly on a character that isn’t going to get UMD in-class or have high Charisma.

Other meaningful Devotions^CC include Animal (flight! limited, sure, but still!), Law (attack bonuses; you need them), and Knowledge (you probably won’t have great Int, but it’s a minimum of +1 to attack and damage no matter what you roll, and it’s not super-hard to get +2 or +3). Knowledge Devotion is so good that it’s worth considering being a cloistered cleric^UA just to get it. Under fractional BAB, Monk 2/Cloistered Cleric 1 has +2.0 BAB, making it a good time to start taking +1.0 BAB classes.

Paladin

Two levels of paladin gets you Divine Grace, which you shouldn’t care about in the least since you should have minimal Charisma, but the Serenity feat^DC allows you to switch Divine Grace to Wisdom, and then all of a sudden it matters a whole lot. It also swaps other paladin class features; Smite Evil 1/day isn’t impressive, but you’ll have it and it will use Wisdom instead of Charisma.

Really, I only recommend this route if you’re going high-Wisdom, which your question indicates you are not. If you change that, I also recommend Intuitive Attack^BoED as that will reduce your need for Strength; it functions like Weapon Finesse, but for Wisdom instead of Dexterity and for simple weapons (including unarmed strikes) rather than light ones.

And the problem with this is that you already need two feats (Great Fortitude and Power Attack) by 5th level in order to qualify for fist of the forest, and paladin wants another two feats. Non-humans only get two feats by 5th unless they have flaws,^UA which means you can’t actually take Intuitive Attack and Serenity until later. Being human helps (you can get one of them) and flaws eliminate the problem, but if those aren’t options, those paladin levels don’t do a lot for you until 6th or even 9th.

Psychic Warrior^XPH

Another ¾ BAB class, sadly, but this one is a powerhouse. The first two levels have bonus feats from the fighter list, or any Psionic feat, so that’s a ton of options. More importantly, you get some powers, including the excellent expansion, and if you really want to, you can take Monastic Training^EbCS (psychic warrior) and Tashalatora^SoS to have psychic warrior progress your various monk class features. In fact, since neither feat requires levels in monk, you could replace monk entirely with this class.

Ranger

Fist of the Forest requires a fair few skills, and they’re kind of ranger-y. Ranger has full BAB and 6+Int skills. It’s boring, but it’s thematic and it will help you out. I wouldn’t bother with more than one level, though. I’d try to avoid even that if I could.

Warblade^ToB

OK, now we’re getting somewhere. Warblade has d12 HD, 4+Int skills, and a few maneuvers – which do excellent things for your mobility and versatility. Diamond Mind is excellent, as it is based on Concentration (which, obviously, uses Constitution), and Stone Dragon can do great things for that whole survivability thing. In particular, knowledge of a Strone Dragon maneuver can let you take Stone Power^ToB instead of Power Attack, trading attack penalties for temp HP every round. That can seriously extend your HP, as you keep regaining temp HP.

Personal Suggestion

Dragon of the Stony Path

Assuming fractional BAB,

Monk 2/Warblade 1/Cloistered Cleric 1/Warblade +1/Fist of the Forest

Cloistered Cleric should definitely get Travel Devotion and Knowledge Devotion. For the third Domain, Magic and Time are strong contenders, as is Law Devotion. But Undeath Domain is probably the best choice, not because it’s particularly amazing, but because Extra Turning means you can dump Charisma and get 4 uses out of Travel Devotion in a day. Travel Devotion is fantastic.

Warblade is more interesting. That first level, I’d probably take stone bones, considering your goals, and sapphire nightmare blade to give your Constitution some offensive use. Douse the flames or leading the attack are my picks for the third maneuver, but either works. The stance is a toss-up too, but I favor bolstering voice or leading the charge.

Then, because you have a Stone Dragon maneuver, you can pick up Stone Power at 3rd level. This meets fist of the forest’s Power Attack requirement, and is decidedly more survival-oriented. It’s also just better when you aren’t wielding a two-handed weapon.

For the second warblade level, your Initiator Level is 3 or more, so you can take a 2nd-level maneuver. Plenty are good, but mountain hammer is more-or-less definitively the one you want to take. It’s good in combat, and great out of combat. Seriously, get mountain hammer.

Worth noting, if you have the flexibility to change the order of your classes, 1st level has some special features (maximized HD, quadrupled skill points) that monk does not make good usage of. Either of the other classes is better; warblade for HP or cleric for skills.

Zen Knight

Monk 2/Paladin 2/Warblade 1/Fist of the Forest

Using Serenity and Intuitive Attack to add Wisdom to all saving throws (twice to Will!) and to your attack rolls, as well as your AC of course. Warblade either at 3rd, so you can take Stone Power, or at 5th, so you can take mountain hammer. If retraining is allowed so you can swap out Power Attack for Stone Power once you have your warblade level, it’s far better at 5th. If not... ugh, that’s an unpleasant choice.

Remember the problems brought up in the paladin section about actually taking Intuitive Attack and Serenity while qualifying for fist of the forest.

But this basically isn’t worth it unless you are going all-in on your Wisdom score. Paladin does not add very much – not nearly as much as cleric, swordsage, or warblade – other than the opportunity to use Wisdom for almost everything you do.

Note that unarmed swordsage is so much better than monk here. It’s always true, but especially so in this case. Swordsages get Wis-to-AC, but can still wear light armor. It would also get you a bunch of maneuvers, potentially helping with the mobility issues you have because you don’t have Travel Devotion.

On which note, Monk 1/Cloistered Cleric 1 (assuming fractional BAB) is far better than Monk 2, and maybe even than Swordsage 2: you get Travel Devotion.

Monk 1/Paladin 4/Fist of the Forest

Only worth noting because Serenity means that Paladin 4’s Turn Undead is 3+Wis uses per day instead of 3+Cha uses. Then you can take Travel Devotion as a regular feat. Don’t really think it’s worth it, myself, unless you cannot use fractional BAB. Particularly since you already have issues getting all the feats together.

SAD Wisdom-sensei

Unarmed Swordsage 1/Paladin 2/Unarmed Swordsage +3/Fist of the Forest

Note that this build qualifies to take fist of the forest at 6, but doesn’t because Divine Grace and Insightful Strikes are yummy.

Intuitive Attack and Serenity are assumed. Again, accomplishing that as a non-human without flaws is problematic. At least here you can delay Great Fortitude until 6th, that helps. Also, swordsages really want Adaptive Style^ToB...

This build gets Wisdom to AC (even while wearing light armor), all saves (twice to Will!), attack (with Intuitive Attack), and damage (when using a strike from the discipline chosen for Discipline Focus). Stone Dragon is a decent choice for Discipline Focus, as it will give you Weapon Focus (unarmed strike) as well as be a discipline you want to use often, but note that Stone Dragon has the unfortunate limitation of only being usable while standing on the ground. This becomes a serious problem at higher levels, when it becomes so crucial to get flying in order to engage foes.

Sources

• ^BoED – Book of Exalted Deeds
• ^CC – Complete Champion
• ^DC – Dragon Compendium
• ^EbCS – Eberron Campaign Setting
• ^SoS – Secrets of Sarlona
• ^SS – Savage Species
• ^ToB – Tome of Battle
• ^UA – Unearthed Arcana
• ^XPH – Expanded Psionics Handbook