This is one of the sample builds I'm thinking of putting in my guide. 

This build was sort of requested by Ytterbium_Dragon. 

Goals of the build: do as much damage as possible using vulnerabilities while putting enemies in a lose-lose situation via divine challenge and arcane ripostes. 

I didn't pick encounters or dailies, because they do little to increase (and can even decrease) warlock DPR.

I picked level appropriate gear.

====== Created Using Wizards of the Coast D&D Character Builder ======
sun warlock, level 30
Dragonborn, Warlock, Morninglord, Demigod
Eldritch Blast: Eldritch Blast Constitution
Eldritch Pact: Infernal Pact
Arcane Admixture Damage Type: Arcane Admixture Thunder
Arcane Implement Proficiency: Arcane Implement Proficiency (Staff)
Divine Spark: Divine Spark Constitution
Divine Spark: Divine Spark Charisma
Dragon Breath Key Ability: Dragon Breath Constitution
Dragon Breath Damage Type: Dragon Breath Cold
Arcane Admixture Power: Hellish Rebuke

FINAL ABILITY SCORES
Str 15, Con 28, Dex 15, Int 10, Wis 12, Cha 24.

STARTING ABILITY SCORES
Str 11, Con 18, Dex 13, Int 8, Wis 10, Cha 12.

AC: 43 Fort: 41 Reflex: 37 Will: 40
HP: 185 Surges: 15 Surge Value: 55

TRAINED SKILLS
Arcana +20, Religion +20, Thievery +22, Intimidate +29, Endurance +29

UNTRAINED SKILLS
Acrobatics +17, Bluff +22, Diplomacy +22, Dungeoneering +16, Heal +16, History +17, Insight +16, Nature +16, Perception +16, Stealth +17, Streetwise +22, Athletics +17

FEATS
Level 1: Armor Proficiency (Chainmail)
Level 2: Arcane Implement Proficiency (staff)
Level 4: Implement Expertise (rod)
Level 6: Draconic Spellcaster
Level 8: Soldier of the Faith
Level 10:Dual Implement Spellcaster
Level 11: Radiant Breath
Level 12: Lasting Frost
Level 14: Called Shot
Level 16: White Lotus Riposte
Level 18: White Lotus Master Riposte
Level 20: Wintertouched 
Level 21: Warlock implement expertise
Level 22: Warding Curse
Level 24: Astral Fire
Level 26: Arcane Admixture
Level 28: Echoes of Thunder
Level 30:Weakening Challenge

 POWERS
Warlock utility 2: Fast Hands
Warlock utility 6: Red Leeches of Nihal
Warlock utility 10: Etheral Sidestep
Warlock utility 16: Warp Space
Warlock utility 22: Wings of the Fiend

ITEMS
Rod of the Dragonborn +6, Eladrin Spiritmail +6, Boots of Caiphon (epic tier), Staff of Ruin +6, Symbol of Divine Light +4, Hands of Hadar (epic tier), Razordark Bracers (paragon tier), Cloak+5, Ring of the Radiant Storm (paragon tier), War ring, ankmon's bracers, Siberys Shard of the Mage
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At will teleport of 4 spaces, which is enough to trigger shadowwalk consistently

Hellish rebuke does fire, thunder, cold and radiant damage. It causes cold vulnerability 5 and radiant vulnerability 15. 

If needed, boots of caiphon are used to always trigger hellish rebuke secondary damage via a minor action each turn.

Hellish Rebuke

To hit: 15 (base)+9 (con)+1 (prime shot)+ 6 (enhancement) +2 (CA)+3 (rod exp)+3(draconic spellcaster)+1 (bloodied)=40 versus 41 reflex= 95% hit ratio

Roll all radiant damage twice and use the better result (ring of the radiant storm)

Primary Damage: 7 (base)+9(con)+12 (enhancement)+6(item)+ 10.5 (curse) +5 (called shot)+5 (cold vulnerability)+15 (radiant vulnerability)+3(astral fire)+3 (echoes of thunder)+7(hands of hadar)+5.5 (Ankmon's Bracers)+5(dragonshard)+4(rolling 7d6+1d10 twice approximation given by Molecule)= 97 average damage

Critical hit damage= 12 (base)+9(con)+12 (enhancement)+6(item)+ 18(curse) +5 (called shot)+5 (cold vulnerability)+15 (radiant vulnerability)+3(astral fire)+3 (echoes of thunder)+12(hands of hadar)+10 (Ankmon's Bracers)+ 21(critical bonus dice)+3.5(war ring)+5(dragonshard)+2.55(rolling 7D6 twice approximation given by Molecule)= 142.05 

Secondary Damage: 7 (base)+9(con)+12 (enhancement)+6(item)+ 5 (cold vulnerability)+15 (radiant vulnerability)+3(astral fire)+3 (echoes of thunder)+5(dragonshard)+1.4(rolling 2D6 twice approximation given by Molecule)= 66.4 average damage.

Hellish rebuke DPR= 159.735

.10*(142.05+66.4)=20.845

.85*(97+66.4) =138.89

95% of the time, the enemy must either take Divine challenge or arcane riposte (9 (con)+15 (radiant vuln)+5 (cold vuln)=29 damage) & master riposte damage (159.33 damage).  Assuming they always take the smaller damage, which is divine challenge, they will take 9(base)+6(cha)+15 (radiant vulnerability)=30 damage, they also will be weakened.

Average DPR will be somewhere around 188.235

Defenses

Defenses are reasonably good once warding curse and shadowwalk are added in (+4 to all defenses).  This warlock is also extremely tough, with a good number of hp, a high surge value, and 15 surges. 

Mobility is decent, with an at-will teleport of 4 and a speed of 6. 

Please let me know if I made mistakes anywhere or could up my dpr somehow.

Oct 30, 2009 -- 5:09PM, Melos wrote:

How are you able to apply Divine Challenge each round?  The damage from it only works for the first attack the enemy makes so you need to keep applying it.

You don't need to reapply DC.  I was however assuming I didn't kill the enemy when I hit it.

Oct 30, 2009 -- 5:09PM, Melos wrote:

You are attacking reflex 39 but the standard is Level + 12, so 42.  Not a big deal since this does not change the 95% chance to hit.

You're right.  The 39 instead of 41 was a typo, which doesn't change the dpr outcome.  For some reason the DPR builds on Borg's top striker list typically measure against NAD values between 40 and 41 instead of 42.  Until they start measuring against 42, I'll measure my builds against thier baseline of 41.   

Oct 30, 2009 -- 5:09PM, Melos wrote:

I don't think you would include the secondary Hellish Rebuke damage in critical hit calculations.

You don't max secondary damage on a crit, but you still get it.  Otherwise, you'd be better off not criticing at all with multi-damage roll powers like Hellish Rebuke.

Oct 30, 2009 -- 5:09PM, Melos wrote:

You could use it to get an extra +1 or use Ankhmon's Bracers instead of the item set ones.

 Wow, I forgot ankmon's bracers.  Good catch. 

Oct 30, 2009 -- 5:09PM, Melos wrote:

You are relying a lot on damage types adding keywords to the attack, which is not something that everyone agrees on.

I go by the following:

"A creature that is vulnerable to a specified damage type usually takes a specific amount of extra damage when it takes damage of that type, or it suffers a specific effect. For example, a creature that has vulnerable 10 radiant takes 10 extra radiant damage when an attack deals radiant damage to it or when it takes ongoing radiant damage."

In short, if it does damage of a type, the vulnerability is triggered. 

Oct 31, 2009 -- 1:26PM, Molecule wrote:

If you're curious, my math suggests that if all the damage dealt by the power is treated as radiant (which I believe is the case but my knowledge here is kind of hazy), the expected value from rolling 7d6 twice (curse + power + gloves) is 27.05 (as opposed to the expected value of 24.5 from only rolling it once).  Also, the expected value from 1d10 twice pick the highest one is 7.15 rather than the 5.5 expected from just one die.

That is cool.  I was playing around with math trying to figure out how to do it.  My thought was to generate a population and assume one roll is, on average, one standard deviation high and the lower rolls is, on average, a standard deviation low, but I don't think that actually is how it works.

If it's not too much trouble, I'd be curious to see how you got your numbers so I could add them into the totals and accurately depict their value in my handbook.

Oh I also forgot to add in a dragonshard, so I redid some of my defensive items to get the money, and my at-will DPR is now up to 154.75.

Nov 1, 2009 -- 3:55AM, Molecule wrote:

There is a distinct possibility that there is a much more elegant way to do it, but I don't know what it is.

There is an elegant solution but it involves deriving maximum likelihood estimators for each system.  Your brute force approach is probably less prone to human error.

en.wikipedia.org/wiki/Maximum_likelihood

Hiya guys,

I just want to give a little bump to see if there were any more suggestions or corrections before I added this to my guide.

I also  awaiting confirmation from Molecule that rolling damage twice boosts Hellish Rebuke damage to DPR= 159.33