Just in case anyone wants to try this build here is what I ended up with, including what I would change.
Shadowdancer: Monk (Forbidden Fist) + Rogue (Trickster).
The build really relies on Soul Mirror, Riposte and Disengagement attacks to deal with mobs whilst using Enfeebled affliction plus DoTs to deal with strong single targets. With high Deflection, high Crit rate and Rogues damage bonuses' you can kill anything. The part I had issues with was surviving but I'll recommend a few changes that should help.
This build isn't really about using the Forbidden Fist ability for damage, its more for the Enfeebled affliction or providing an alternative damage type. I never really stacked it up because it had such a short timer vs the characters recovery/action speed. Most of the characters time was spent casting with the character doing damage automatically.
Race
Orlan is best for the extra RES but DON'T USE WILD ORLAN, or any sub-race that has a Resistance as this will affect your wounds and reduce the number of afflictions
Attributes
Max PER and RES.
I wouldn't add anything to INT or DEX, if anything I'd steal a couple of points from DEX to add to MIG and CON.
As we aren't stacking up the FF ability, the self damage is less of a concern whose damage scales with MIG and length with INT, but you do have to be aware of it. Not putting points into INT will mean less time on your abilties and DoTs but we can add INT through an ability and items.
Abilities
Weapon & Shield + Soul Mirror + Riposte + Persistent Distraction + Mirrored Image and/or Llengraths Displaced Image + Ryngrims Repulsive Visage (if enemies not immune to RES) + Deep Wounds - Get Deflection as high as possible and cause enemies to disengage create a lot of passive damage. Need more Engagement as those are the only targets that get attacked when they disengage. Lowering there PER helps make them miss more often.
Swift Flurry + Heartbeat Drumming + Dirty Fighting for more crits and more attacks on those Riposte and Disengagement attacks.
Blade Turning - Help defend against Resolve immune/resistant enemies or redirect abilities applied by there weapons. Long recovery and not very long effect time.
Thunderous Blows - More MIG and Pen so those Riposte and Disengagement attacks hurt even more plus more healing.
Enlightened Agony - Flat 5s removed from hostile effects and halved. Hence want to be hit (but not too hard) with Fort, Ref or Will targeting abilities. Smart for more Int helps with ability length.
Iron Wheel - More CON so aren't too weak on FOR defence, plus more HP and DR to give time to heal.
Gouging Strike - Use blunderbuss (or two) to apply this to AOE for the Blind and small but never-ending RAW DoT.
Deathblows - Lots of extra damage if can apply afflictions to the enemy (Terrify, Distract/Blind). If not solo should be easy for companions to do this, even if they hit this character it shouldn't last long help heal.
Ring The Bell - The main DoT ability. I wait until Enfeebled is down to a few seconds on the target, then use RtB which gets the +50% time buff, then wait for Enfeebled to end and reapply, giving another +50% hostile ability time. If you get RtB high enough doing this, you can repeat the Enfeebled trick, let it end and reapply, unless Enfeebled crits and ends up too long that 50% extra doesn't add very long to RtB.
Theres not many points left, mostly early as nothing "key" there, I tried at various times:
Escape - Handy and only one point. 50 more DEF for ~5 seconds can help in a bad situation.
Parting Sorrow - Helps keep wound generation up when enemies die or disengage. If don't need more wounds then skip.
Arms Bearer - For the 3rd slot for Blunderbuss' opener.
Two Weapon Style - Really not needed, most damage is passive or DoTs.
Rooting Pain - Due to cast times, i'd be at 10 wounds most of the time, so this wouldn't trigger. Small damage but the Interrupt was probably more use but very optional.
Uncanny Luck + Improved Critical - More damage done and less taken. +10% more crit damage isn't much when you have Deathblows but against bosses with lots of immunities its a bit extra to help.
Force of Anguish - Rarely used, would Enfeeble and apply DoT then kick the enemy away, especially if immune to RES afflications.
Raised Torment - Handy to Stun enemies behind your target and use some Wounds up if Enfeebled applied and don't need to cast Enlightened Agony, Thunderous Blows or Blade Turning.
Skyward Kick - Helps with single target damage, interrupt and disable them for a bit.
Arterial Strike - I didn't tend to use as wasn't using Blunderbuss at the time and Guile is limited and lots of other key abilities use it.
Toxic Strike - Same trick as RtB, damage numbers get silly BUT so many boss enemies are immune to it and 3 guile is too much. Weakened is also wasted because you have Enfeebled from the FF ability.
Two great Watcher ability that synergise well for harder fights (1/rest):
No Time for the Lost - Foe AoE Distracted, AoE -10s hostile effects and +10s beneficial effects, Steadfast. Extra RES which you can't do otherwise. +10s is great to extend short abilities like Blade Turning.
Awe of the Death Herald - Target Frightened, MIG & PER Inspiration for long time, no other ability gives PER for Monk/Rogue.
Main Weapons
Fire In The Hole + Hand Mortar - For applying Gouging Strike.
Mohorā Tanga + Small Shield - More accuracy, spear modal for more engagement, RAW DoT, more pen + damage with Survival skill.
Kapana Taga + Small Shield - Chance of Daze, more engagement + damage, more raw damage, Immune to Flanking (protect that DEF!).
Shield is Tuotilo's Palm once can get it. Counts as weapon so two hits on Full Attack abilities, riposte attacks and disengagement attacks, two chances of crit so more chance of triggering more attacks! More riposte chance or more DEF+REF per wound, either is valid but DEF is hard to increase so i'd take that.
Early/Mid game options (I used)
Xoti's Sickle - Best early game option, adds a bit of DEF, more damage per kill (religion increases), and Raw DoT on near death enemies to help finish them. Possibly applied by a Riposte or Deflection attack, so good!
Marux Amanth - Extra Accuracy, burn AoE chance and unique ability Worthy Sacrifice.
Sun and Moon - Two hits so more chance of crit and triggering more attacks.
Rannigs Wrath - Extra Accuracy plus more from the Rapier modal, chance to recover immediately and extra DEF if your crit.
Main Items
Armour - Fleshmender / Cabalists Gambeson / Garari Cuirass.
Head - Whitewitch Mask for better Illusion level and free Ryngrim's Enervating Terror when Bloodied. Mine lost its abilities (not sure why) so I switched to Heaven's Cacophony for +2 INT and added Shock damage per weapon hit (see a theme, all those two weapon riposte and disengagement attacks).
Boots - Shorewalker Sandals for +1 RES. Footsteps of the Beast can be a handy way of applying another affliction to enemies to enable Deathblows. If your confused it will help with wounds and healing to!
Cloak - Deflection +7, need all can get. The Magnificent Escape Cape is an option, gives free Escape but I prefer the simple always active +7.
Gloves - Hylea's Talons for more enemy RAW DoT damage. Could apply to yourself but its a short DoT with all the hostile ability reductions which is self healed when it ends and gives wound.
Belt - Girdle of Mortal Protection for more CON and crit reduction. Another option is Undying Burden gives same CON but extra Second Wind and damage reduction as you lost HP rather when your crit. Even with 150 DEF I was getting crit cos some enemies had 200 accuracy.
Ring 1 - Greater Regeneration for HP/S
Ring 2 - Voidward to reduce damage from FF ability, Hylea's Talons and any raw damage applied by enemies until you can remove it with Enlightened Agony and your other hostile effect reductions.
General Fights
If can group enemies then Gouging Strike them with Blunderbuss.
Apply instant cast defences Mirrored Image and/or Llengraths Displaced Image.
Swift Strikes.
Enlightened Agony.
Ryngrim's Enervating Terror OR Blade Turning.
Thunderous Blows when you can.
If all abilities up use FF and pick your Ring The Bell target carefully as don't have lots of Guile.
I'm sure better players than me could solo with this but it was fun. Just don't try and do too much, I was so focused on maximizing DoT's I was struggling as the main tank (or solo attempts) hence the adjustments i'd make but couldn't to subrace and starting attributes. I enjoyed it so much I might try a solo run with it, maybe not on PotD though...
Enjoy!