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 attacksSS; 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 DevotionsCC 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 clericUA 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 featDC 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 AttackBoED 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 WarriorXPH
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 TrainingEbCS (psychic warrior) and TashalatoraSoS 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.
WarbladeToB
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 PowerToB 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 StyleToB...
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
Best Answer
Duskblade 13/Crusader 1/Jade Phoenix Mage 6 seems to me to be much superior to Duskblade 20. You hit the really big duskblade class feature and retain your highest-level spells.
The issue is timing. The best levels to take Crusader are 5th, 9th, or 13th. Coincidentally, however, 5th, 9th, and 13th are also the levels where it is most painful to have a single level of crusader rather than being a single-classed duskblade, as those are the levels at which you get new levels of spells (and full-attack arcane channeling, in the case of 13th). You have two competing goals: get the next spell level (and full-attack arcane channeling) as soon as possible, while having maneuvers for as long as possible, since they are useful.
Therefore, I recommend taking the crusader level at 6th, 10th, or 14th; that is, I’d take the next spell level first, rather than the maneuvers. Here’s a breakdown of each option:
Duskblade 5/Crusader 1
You can take 2nd-level maneuvers with your first five maneuvers. This means, primarily, that you will have mountain hammer for the longest possible time, which is awesome. Other than that, though, you’ll probably still take a number of 1st-level maneuvers.
Duskblade 9/Crusader 1
You can take 3rd-level maneuvers and stances with your initial set; you can skip crusader’s strike for revitalizing strike, you can still take mountain hammer, and the amazing white raven tactics is available to you. Thicket of blades opens up as an interesting stance option; martial spirit is pretty small at these levels, and thicket of blades greatly improves your presence on the battlefield.
Duskblade 13/Crusader 1
Clearly if you haven’t taken crusader by this point, you should. Duskblade has little to offer, so you lose almost nothing at this point. The disadvantage of waiting this long is that you haven’t had maneuvers at all until this point. The advantage, on top of duskblade features ASAP, is divine surge, an excellent offensive maneuver.
The Awkward Bit
OK, so now that we’ve covered how to do it, there’s one other thing to consider: you cannot use arcane channeling and a martial strike at the same time. Arcane channeling requires a standard action attack or a full-attack, so the attack(s) you get from a strike don’t count. This makes strikes massively less useful to you than they would be to others. A boost or counter heavy selection of maneuvers solves this issue; you could do pretty well with defensive rebuke, shield block, and white raven tactics. But missing out on fantastic options like mountain hammer, tactical strike, the various healing strikes, and divine surge is a disappointment.
It also means you don’t have especially great mobility. You have invested 13 levels in duskblade to allow you to full-attack with spells, so you really do want to be making full-attacks. Crusader doesn’t help with that. Swordsage or warblade would help a little, since Tiger Claw is pretty good at that (sudden leap, arguably pouncing charge), but cleric for Travel Devotion or barbarian for Lion Spirit Totem (Pounce) might be better. Those options don’t lead into a great prestige class like jade phoenix mage, but they still might be better options.
The Other Thing
Finally, item-based healing is generally sufficient in 3.5. In-combat healing is rarely an optimal strategy, barring emergencies; the crusader is far better at this than other classes, but you shouldn’t usually need it. The aura you describe all-but-eliminates the worst emergencies, too. Wands and healing belts are quite sufficient for out-of-combat healing. As Jeor Mattan mentioned in comments, the real draw of actually having a cleric is the various options he or she would provide for removing status conditions, since items have HP-healing pretty much covered (and until you get heal, clerics’ HP-healing spells are pretty poor), and crusaders don’t cover that at all.
This is another situation where a level of cleric may be more useful to you: it would allow you to use wands of any cleric spells you like, with no Use Magic Device check. That will cover a lot your needs.