My first warlock (lvl 87) was Apocalypse, which I did not like, don't like running into immunities or having to heavily invest into breaking those.
My second warlock (lvl 92) is Echoing Strike and is absolutely amazing, clears anything, pretty much immortal, immunities don't exist (Demon must be cursed). Also low maintenance as no potion drinking required due to leech.
The last one I created is a summoner warlock, lvl 89 ladder at the moment. I run a Demon and two Defilers to spread the damage to up to 10 other targets. This build also doesn't concern itself with immunities, but you need a good demon: cursed Hephasto with Fanaticism (you need both, else it will suck).
I also tried clearing a lvl 90 terror zone completely naked, zero gear and zero inventory and it worked, no issues here. Which other build can do this? So this build has a very low gear dependency.
Clear speed is slower than Echoing Strike, no question, but it's good enough. The demon is a beast, usually he takes no damage at all, even tier 5 heralds can't do anything. You basically kill them AFK. As far as i noticed, one hit from my demon takes away ~5% of the health of a tier 5 herald, and my gear is really bad (only Spirit sword and Lore helm, so +3 in total).
A fun thing with this build also is, that you can clear rooms without going in or without opening the door, you teleport your demons in and wait 10 - 15 seconds. When they are done, they open the door themselves and come back to you. You can teleport your demons everywhere and they immediately start doing business.
Lol
Meanwhile Mr. Necro has level 38 skeleton mages that don't do anything and skeletons that die in a couple hits and can't do much unless Emilio is there
D2:R