[Janchet]

Looking at all these posts I can name a bunch of counters to your attacks. I play a 70 Undead Shadow Priest and I kill warlocks easily.

#1 If you have imp out for mana then:
a) I can't be silenced.
b) I keep my buffs.
c) you don't have some extra dps. Don't try to dps with an imp as well. Mind Blast + SW:Death is an easy 3000-4000 damage. The imp dies and you lose your extra dps and stamina buff.
Yes you would have more mana and HP at the end but duels usually don't last that long to use that much mana and that extra HP last about 6 seconds in dots.

#2 If you have the Felhunter out:
a) I fear it. It sometimes resists but I usually put up with its dps. Although it is very annoying so this is what you should be using with the Felhunter's abilities.

#3 If you try to use fire/Shadow Bolt:
Silence .... I've only played a warlock up to 48 but I'm pretty sure there are no instant casts for fire spells. This is a problem for you because while my shadow fiend is slowing your casting time, I'm just waiting until you are about to use your immolate/SB or whatever and silence you. You have just lost about 6 seconds which equates to 2000~2500 damage or so in dots.

#4 If you use Shadow Ward I dispel it. If you use Fel armor or demon armor I dispel it. Sure it takes up 3 seconds for my but you lost some of your armor/shadow protection so it works for me.

#5 Spell stone ... I haven't experimented much with it but it only takes off MAGICAL effect correct? Then Devouring Plague will not be affected because it is classified as a disease. Its still a very nice counter to my dots. Re-applying them is a cake but it wastes my mana which is your goal. Not many warlocks I face use it. Its just sitting in the back of their spell books.

#6 Fears:
a) Will of the Forsaken, Insignia of the Horde, 70 shadow resistance. It is a bit hard to fear. However, like people have been saying, it is worthwhile if you get it off. I have fear too which I generally use early on. It is only on a 23 second cooldown because I have arena set #3 Gloves ... the only PvP armor I have. =( Pain for anybody to get feared and warlocks and priests are no exceptions. Oh and Priest have fear ward now so your first fear is null unless your felhunter takes it off early on. Deathcoil doesn't count as a fear so use it when I am casting/healing.

#7 Drain Mana/Life:
No ... just no. Most pointless thing ever when your dueling a Shadow Priest because your dots are going to be dispelled which you have to constantly reapply unless you are using Unstable Affliction ... in that case I silence you or fear you for it.

I think that covers most of it ... HEALTHSTONES! Those annoying little health potions! It usually gives me a false sense of security if you have one and use it. My finishing move for almost any battle is Mind Blast and SW:Death which is the final dps needed to kill. It sometimes happens that I kill myself with SW:Death. My personal problem but use your healthstones.

Basically it comes down to raw skill. Can you out-think your opponent, thinking of your upcoming Cooldowns coming off, when to use those cooldowns, what curse is best for the situation, when to use fear, when to use your pet's silence, and all that good stuff. It comes down to how well you play your class and trying to predict what will happen next. This is why I love Warlocks and Shadow Priests. I need to think more than to spam frost bolt or sinister strike (DAM YOU TO HELL YOU CHEAP BASTARD ROGUES!). Well I'm open to criticism and counters to my counters or if some of my logic was faulty/unclear. Have dueling!