OK, From the looks of it, you want the following:
- Stealthy
- Leadery needs to be able to command numerous minions
- Level Appropriate, but formidable.
You want this guy
Danjani, He's a L4 Tiefling darkblade solo. Make him a human by making one small change, instead of his racial power give him a reroll on an attack.
Dajani, Tiefling Darkblade
Medium natural humanoid
Level 4 Solo Lurker
XP 875
Initiative +12 Senses Perception +5; low-light vision
HP 224; Bloodied 112
AC 21; Fortitude 16, Reflex 20, Will 16
Resist 12 fire
Saving Throws +4
Speed 7
Action Points 2
Poisoned Short Sword (standard, at-will) Poison, Weapon
+9 vs AC; (+10 against bloodied target)1d6+4 damage, and Dajani makes a secondary attack against the same target.
Secondary Attack +10 vs Fortitude; ongoing 10 poison damage (save ends).
Double Attack (standard, at-will)
Dajani makes two poisoned short sword attacks but cannot make both attacks against the same target.
Demonic Frenzy (immediate reaction, when attacked by an adjacent enemy while bloodied, at-will)
Dajani makes a frenzied short sword attack against the enemy; +9 vs AC; (+10 against bloodied target)1d6+4 damage.
Secondary Attack +10 vs Fortitude; ongoing 10 poison damage (save ends).
Cloak of Lurking (move; at-will) Teleportation
Dajani teleports 5 squares and becomes invisible until the end of its next turn.
Infernal Wrath (minor; encounter, recharges when first bloodied)
Dajani gains a +1 power bonus to its next attack roll against an enemy that hit him since his last turn. If the attack hits and deals damage, Dajani deals an extra 3 damage.
Alignment Chaotic evil Languages Common, Supernal
Skills Bluff +13, Stealth +15
Str 13 (+3) Dex 20 (+7) Wis 14 (+4)
Con 16 (+5) Int 13 (+3) Cha 16 (+5)
Equipment: cloak, cult tunic, 2 poisoned short swords, Naarash talisman, boots of striding , leather armor .
That's a tough foe, if you want something a bit more run of the mill, I recommend going the elite route. Kelson is a good monster here.
Kelson
Small natural humanoid, halfling
Level 5 Elite Skirmisher (Leader)
XP 400
HP 120; Bloodied 60 Initiative +9
AC 20, Fortitude 16, Reflex 19, Will 16 Perception+7
Speed 6
Saving Throws +2 (+5 against fear effects); Action Points 1
Traits
Gang Leader Aura 3
Allies gain a +2 power bonus to saving throws while in the aura.
River Rat Tactics
Kelson has combat advantage against any enemy that is adjacent to at least one of his allies.
Standard Actions
Short Sword (weapon) At-Will
Attack: Melee 1 (one creature); +10 vs. AC
Hit: 2d6 + 6 damage.
Throwing Dagger (poison, weapon) At-Will
Attack: Ranged 10 (one creature); +10 vs. AC
Hit: 1d4 + 5 damage, and ongoing 5 poison damage (save ends).
Flickering Blades At-Will
Effect: Kelson uses short sword against one enemy, shifts up to 3 squares, and then uses throwing dagger against a different enemy.
River Rat's Gambit Encounter
Requirement: Kelson must be bloodied.
Effect: Kelson makes a basic attack. If the attack hits, the target takes 2d6 extra damage. If the attack misses, Kelson takes 1d6 damage.
Triggered Actions
Second Chance Encounter
Trigger: An enemy hits Kelson with an attack.
Effect (Immediate Interrupt): The triggering enemy must reroll the attack and use the new result.
Skills Acrobatics +12, Bluff +9, Stealth +12, Streetwise +9, Thievery +12
Str 14 (+4) Dex 20 (+7) Wis 11 (+2)
Con 12 (+3) Int 10 (+2) Cha 15 (+4)
Alignment Evil Languages Common
Equipment: dagger x10, leather armor , short sword .
All that to say, forget the race, focus on getting the powers, level and role right, and then just reflavor the monster however is required for your campaign. 4e monsters are just a set of powers to hang a character on. The name and race rarely matter, just use them as a canvas on which to paint your world.