I just tested it out - the Bard/RDD/Assassin/?
It works, but really only with an Earth Genasi:
The Reaper:
20/10/12/14/6/12 (constantly upping Strength). Use a Spear or Staff for Disarm (until you get a Scythe or Falchion).
Bard for levels 1-5
1. Skills: Concentration 4, Hide 4, Listen 4, Lore 4, MS 4, Perform 4, Tumble 3, carry-over 5.
Feats: Wild Child, Able Learner; Spells: Amplify, Joyful Noise
2. Skills: Concentration 1, Hide 1, Listen 1, Lore 1, MS 1, Perform 1, Spot 2, Tumble 2, carry-over ?
3. Skills: Concentration 1, Hide 1, Listen 1, Lore 1, MS 1, Perform 1, Tumble 1, carry-over ?
Feat: Knockdown; Spell: Sleep
4. Skills: Concentration 1, Hide 1, Listen 1, Lore 1, MS 1, Perform 1, Spot 1, Tumble 1, carry-over ?
Spells: Mirror Image, Silence.
5. Skills: Concentration 1, Hide 1, Listen 1, Lore 1, MS 1, Perform 1, Tumble 1, carry-over ?
Spells: Bladeweave (SOZ), Identify
Assassin for 10 levels:
Skills: drop Concentration & Perform. Concentrate on the others, primarily: Hide,MS, AND Tumble (..Spot should be a *very* close "second"). Consider also pumping up Set Traps, even to the detriment of Listen.
Level 6 Feat: Disarm
Level 9 Feat: Improved Disarm
Level 12 Feat: Improved Knockdown
Level 15 Feat: Whatever you want - AND also take into consideration if you get any bonus feats from your 4th class. My preference is for Martial Weapons here (and NW9 for 5 levels that does NOT have this feat latter). What you select here may also effect the next feat at level 18. Note that up until this point you should have been using a Spear or Staff (..the only simple weapons that are Large - which is important for Disarm). IF you select Martial Weapons here then you can start using a Falchion or a Scythe.
RDD for 10 levels:
Again, concentrate on your "core" skills: Hide, MS, Tumble, (..& to a slightly lesser degree: Spot).
Level 18 Feat: Again, what ever you want. IF you followed with my suggestion of Martial Weapons at level 15 THEN you should select Improved Critical for either Scythe or Falchion. Scythe will give you MUCH bigger criticals, but less often. Falchion will give you much smaller criticals but far more often. In your consideration note that the NW9 class at 5th level has the "ALL Out Assault" feat that works particularly well with the Scythe.:mischief: You could of course though swap-out weapons when using that once-per-day feat.
Level 21 Feat: Great Strength 1
Level 23 Feat: Great Strength 2
Level 25 Feat: Great Strength 3
Final 5 levels:
..are up to you. Again, my preference is for the NW9. It has 2d6 of Sneak Attack, +10 speed (which is important for moving away quickly to Hide if your Death Attack Paralysis didn't work AND your Knockdown Failed), some protection for others, High BAB, and of course All Out Assult - which is pretty much what a real Assassin wants! (i.e. something close to one-shot insta-death.)
Level 27 Feat: Great Strength 4
Level 29 Feat: Great Strength 5
Final "native" Strength = 40!
All-in-all a pretty evil SOB! Note that in addition to the spells, the Bard also has a +1 to attack "Inspiration" that can be toggled on all the time (..or an AC bonus if you would prefer). There are of course multiple feats given by each class that have not been listed.
Valkos:
In your case just keep to the Bard class for your final 5 levels. Don't worry about the starting Charisma either - the RDD class has those extra 2 points for your 4th level spells at 10th level Bard. (..also note that the +1 attack inspiration elevates to +2 at Bard level 8.) Those additional skill points should be welcome too.