I've been 4 boxing warlocks for a while now. With 4+ levels on the early outland instances, I've been able to successfully 4-man them. Any time I've gone in with a healer or tank we've roled straight through them. But of course, you don't want to limit your team, so I can't really say much in the way of advice for you.



PvP, however, has been simply amazing. Where my locks are human, I usually forego the Felpup and just have 4 Felguards out at all time.



I spec'd destro from 1-55 or so. Then I respec'd and got the felguards. I've loved every minute of it. Having that many Felguards in PvP is just insane. Same as the dots. Just running around and dotting someone 8 times so quickly is incredibly fun. I find that leveling with dots is a bit of a waste because they'll never last their full duration. Destro allowed me to usually 1(x4) shot everything, and the Felguards have done all the work for me ever since.



But nothing beats seeds.



I'm still running a setup that involves focusing my main char, but Iv'e found that:

/assist focus

/cast Seed of Corruption

/petattack



...is the best Macro ever. My Felguards always detonate my seeds before I fire off my next round. As a result of this, I've found that firing seeds repeatedly on the same target results in a constant stream of 4k+ damage per 2 seconds to everyone near that target until everything is dead or I'm oom. I've walked out of an AV with over 500k damage per character, 200+HKs and less than 5 deaths while trying to break a massive Horde turtle (30+ characters) stuck at RH. It helped that I had a resto druid healbot.

I haven't tried Arena yet, but am expecting it to go pretty horribly. I've just set a team up the other day. My two rotating Arena partners are a warlock (for fun) and a druid (hopefully we'll have some small measure of success, but I doubt it).