I'm A Banana
Potassium-Rich
So, according to WotC, you should not combine Assassin with a Controller, since Assassins are already sub-par strikers. 
I went ahead and did it.
[sblock]
====== Created Using Wizards of the Coast D&D Character Builder ======
Zavatto, level 11
Gnome, Assassin/Wizard, Unseen Mage
Hybrid Assassin Option: Hybrid Assassin Fortitude
Versatile Expertise Option: Versatile Expertise (Light blade)
Versatile Expertise Option: Versatile Expertise (Ki Focuses)
Inherent Bonuses
Deviant (Intimidate class skill)
Theme: Athasian Minstrel
FINAL ABILITY SCORES
STR 12, CON 12, DEX 21, INT 21, WIS 9, CHA 13
STARTING ABILITY SCORES
STR 11, CON 11, DEX 16, INT 16, WIS 8, CHA 12
AC: 24 Fort: 19 Ref: 20 Will: 19
HP: 62 Surges: 7 Surge Value: 15
TRAINED SKILLS
Insight +9, Intimidate +11, Perception +9, Stealth +17
UNTRAINED SKILLS
Acrobatics +10, Arcana +12, Athletics +6, Bluff +6, Diplomacy +6, Dungeoneering +4, Endurance +6, Heal +4, History +10, Nature +4, Religion +10, Streetwise +6, Thievery +10
POWERS
Basic Attack: Melee Basic Attack
Basic Attack: Ranged Basic Attack
Athasian Minstrel Feature: Poisoned Strike
Gnome Racial Power: Fade Away
Wizard Utility: Ghost Sound
Assassin Feature: Assassin's Shroud
Wizard Utility: Light
Wizard Utility: Mage Hand
Wizard Utility: Prestidigitation
Wizard Attack 1: Scare
Assassin Attack 1: Leaping Shade
Assassin Attack 1: Gloom Thief
Assassin Attack 1: Terrifying Visage
Assassin Utility 2: Cloak of Shades
Wizard Attack 3: Cordon of Bones
Wizard Attack 5: Glitterdust
Stealth Utility 6: Shrouding Gloom
Assassin Attack 7: Shadow Jack
Wizard Attack 9: Face of Death
Wizard Utility 10: Wall of Gloom
Unseen Mage Attack 11: Vanishing Act
FEATS
Level 1: Magic of the Mists
Level 2: Versatile Expertise
Level 4: Assassin's Cloak
Level 6: Shadow Skulk
Level 8: Hidden Insight
Level 10: Mist Walker Illusion
Level 11: Nightmare Master
ITEMS
Magic Ki Focus +3 x1
Adventurer's Kit
Ki Focus
Shared Suffering Cloth Armor (Basic Clothing) +2
Cloak of the Walking Wounded +2
Cloth Armor (Basic Clothing)
Longsword
====== End ======
[/sblock]
The concept for the character is a gnome who really likes to scare the life out of people. The Assassin shadow powers and the Wizard invis/fear/shadow powers had a nice overlap for this archetype.
Given that this is perhaps a horrible combination, I want to make it as effective as possible. The idea is that he spends 90% of his time invisible or Stealthed, via the racial ability, Stealth, and various other add-ons. Giving enemies an almost-always-on -2 or -5 to hit him (from various concealments) helps his mediocre defenses, but I'm worried that he's hurting in the damage category, and perhaps not using the most efficient tricks at his disposal, to get the most out of his limited strikery capabilities. On the bright side, he seems like quite a decent controller!
Anyway, give me some guidance! I know with the Stealth rules being sloppy I'll need to take this up with a DM to see how it's going to work a lot of the time, but I'm quite excited about playing, essentially, The Bogeyman (a gnome).

I went ahead and did it.
[sblock]
====== Created Using Wizards of the Coast D&D Character Builder ======
Zavatto, level 11
Gnome, Assassin/Wizard, Unseen Mage
Hybrid Assassin Option: Hybrid Assassin Fortitude
Versatile Expertise Option: Versatile Expertise (Light blade)
Versatile Expertise Option: Versatile Expertise (Ki Focuses)
Inherent Bonuses
Deviant (Intimidate class skill)
Theme: Athasian Minstrel
FINAL ABILITY SCORES
STR 12, CON 12, DEX 21, INT 21, WIS 9, CHA 13
STARTING ABILITY SCORES
STR 11, CON 11, DEX 16, INT 16, WIS 8, CHA 12
AC: 24 Fort: 19 Ref: 20 Will: 19
HP: 62 Surges: 7 Surge Value: 15
TRAINED SKILLS
Insight +9, Intimidate +11, Perception +9, Stealth +17
UNTRAINED SKILLS
Acrobatics +10, Arcana +12, Athletics +6, Bluff +6, Diplomacy +6, Dungeoneering +4, Endurance +6, Heal +4, History +10, Nature +4, Religion +10, Streetwise +6, Thievery +10
POWERS
Basic Attack: Melee Basic Attack
Basic Attack: Ranged Basic Attack
Athasian Minstrel Feature: Poisoned Strike
Gnome Racial Power: Fade Away
Wizard Utility: Ghost Sound
Assassin Feature: Assassin's Shroud
Wizard Utility: Light
Wizard Utility: Mage Hand
Wizard Utility: Prestidigitation
Wizard Attack 1: Scare
Assassin Attack 1: Leaping Shade
Assassin Attack 1: Gloom Thief
Assassin Attack 1: Terrifying Visage
Assassin Utility 2: Cloak of Shades
Wizard Attack 3: Cordon of Bones
Wizard Attack 5: Glitterdust
Stealth Utility 6: Shrouding Gloom
Assassin Attack 7: Shadow Jack
Wizard Attack 9: Face of Death
Wizard Utility 10: Wall of Gloom
Unseen Mage Attack 11: Vanishing Act
FEATS
Level 1: Magic of the Mists
Level 2: Versatile Expertise
Level 4: Assassin's Cloak
Level 6: Shadow Skulk
Level 8: Hidden Insight
Level 10: Mist Walker Illusion
Level 11: Nightmare Master
ITEMS
Magic Ki Focus +3 x1
Adventurer's Kit
Ki Focus
Shared Suffering Cloth Armor (Basic Clothing) +2
Cloak of the Walking Wounded +2
Cloth Armor (Basic Clothing)
Longsword
====== End ======
[/sblock]
The concept for the character is a gnome who really likes to scare the life out of people. The Assassin shadow powers and the Wizard invis/fear/shadow powers had a nice overlap for this archetype.
Given that this is perhaps a horrible combination, I want to make it as effective as possible. The idea is that he spends 90% of his time invisible or Stealthed, via the racial ability, Stealth, and various other add-ons. Giving enemies an almost-always-on -2 or -5 to hit him (from various concealments) helps his mediocre defenses, but I'm worried that he's hurting in the damage category, and perhaps not using the most efficient tricks at his disposal, to get the most out of his limited strikery capabilities. On the bright side, he seems like quite a decent controller!
Anyway, give me some guidance! I know with the Stealth rules being sloppy I'll need to take this up with a DM to see how it's going to work a lot of the time, but I'm quite excited about playing, essentially, The Bogeyman (a gnome).