It seems to me as if you are really gimping your warlocks dps with that spec. I think that most people who roll locks in a group do full destruction. I prefer a 0/21/40 demonic sacrafice build, that way you could have your succibus out for cc and when not needed just sacrifice her for an extra 15 percent shadow damage, or if you go firelock, which might be the best with fire mages, sacrafice an imp. Just throw up a curse of shadows/elements and dps away. If you really wanted to go demonology I would suggest a 0/41/20 build. That way you get shadowburn, 5 percent more crit, increased range, threat reduction and 70 percent chance to resist interruption, which is really nice when you aoe with hellfire. Instant cast corruption or any other affliction spell isn't going to work out so well with the mages burst damage. I wouldn't suggest putting points into imp imp, imp voidwalker, imp succubus AND felguards... Seems like wasted talent points if you ask me. Pet offtanks work ok for regular instances but they won't last more than 2 hits if you ever plan on doing heroics, if that is what you want to eventually end up doing you should probably practice running with a succubus and cc'ing mobs rather than offtanking. But hey, that's just my thoughts on the topic. I would also suggest demonic embrace for 15 precent more stamina because you're going to have to life tap in order to increase the locks mana pool so he can keep up with the mages.