Here's a quick attempt to truly min-max the power. There's several ways to go:
Standard TWF ranger. Gives you the best damage per hit, good attack rolls.
Fighter Multiclass for Kensai. For that extra reroll, should increase the streak length the most.
Beasthunter Paragon Path. +4 to hit quarried target after spending an action point. But less for two-weapon fighting types overall.
Other class multi-classed with ranger. Can't do this until higher level... but a Fighter or Rogue could up the attack bonuses a bit more this way.
This elf uses every option possible to add to attack bonus except for Beasthunter (which is kinda poor with +1 Dex... at least stormwarden is OK). I ran out of feats to increase damage, so cleric multiclass for bless as as the only easy way to pick up a power bonus to attacks on his own. His magic items are a slight bit above what the DMG gives to make PCs above 1st, but if you compare that to the treasure table it's fairly low, and in general a character who plays up to a level will expect to have about one and a half times as much wealth.
[sblock]Charlie
Elf Ranger 15
Str 20 +5
Dex 12 +1
Con 14 +2
Int 11 +0
Wis 20 +5
Cha 9 -1
Attacks: +3 Prof, +7 Level, +4 Magic, +5 Str
Damage: 1d10+5 Str, +4 Magic, +1 Two-Weapon Fighting
Critical: +4d6+1d10
-At Will-
Twin Strike
Hit and Run
-Encounter-
Disruptive Strike
Hawk's Talon
Clearing Ground
Armor Splinter
-Daily-
Two-Wolf Punce
Attacks on the Run
Blade Cascade
-Utility-
Bless
Weave Through the Fray
Expeditious Stride
Throw Cuation to the Wind
-Feats-
Weapon Prof (Bastard Sword)
Two-Weapon Fighting
Weapon Focus (swords)
Toughness (ranger bonus)
Leathal Hunter
Blood Thirst
Devestating Critical
Initiate of the Faith
Acolyte Power
Elven Accuracy
-Other-
Bladestorm
Stormstep Action
Equipment:
Two +4 bastard swords
+3 darkleaf hide armor
Cloak of Survival +3
Gauntlets of Ogre Power[/sblock]
Round 1: Cast Bless, Move 7, Mark
Round 2: Caution to the Wind, Move 7, Action Point (before attacks if needed to teleport into melee), Armor Splinter, Blade Cascade
Attacks are +22 Vs Ac (+3 Prof, +7 Level, +4 Magic, +5 Str, +1 Power, +2 Unnamed)
Average damage per hit is 17.5: 1d10+12 (+5 Str, +4 Magic, +1 Two-Weapon Fighting, +2 Weapon Focus), not counting crits which pile on 4d6+1d10.
One Hit with Armor Splinter lowers AC by 5, both by 10.
Level 16 Monsters
Thunderfury Boar (15 brute)
HP: 181, AC 27
Needs a 5 to hit with each armor splinter. One reduces the to hit to a 1 for Cascade and will generally end it.
Salamander Archer (15 arterarly)
HP: 114, AC 28
Needs a 6 to hit with each armor splinter. One reduces the to hit to a 1 for Cascade and will almost always end it.
Drow Priest (15 lurker, leader)
HP: 139, AC 28
Needs a 6 to hit with each armor splinter. One reduces the to hit to a 1 for Cascade and will almost always end it.
Githyanki Gish (15th elite Skirmisher)
HP: 226, AC 31
Needs a 6 to hit with each armor splinter. One reduces the to hit to a 4 for cascade, both reduces it to a 1.
Adult Red Dragon (15 solo soldier)
HP: 750, AC 33
(and bloodied breath when reduced to half)
Needs an ll to hit with each armor splinter. One reduces the to hit for cascade to 6, both to 1.
Anyone with better math skill want to take a crack at the damage numbers? What's throwing me off is the odds of missing with armor splinter and needing to use the reroll there...
Yeah, this guy can certifiably kill one non-solo per day without problem, and I'm guessing the elite comes out as better than even odds. But I don't think this is going to down the dragon by any stretch on its own...