Ok, so I just ran two forts, both quite interesting and I wanted to share because they showed some oddities with the warlocks.
First fort, I embark with 4 warlocks/3 skellies. A day in and green goop starts falling out of the sky. Nauseating Slime. It doesn't have any effect on my warlocks or skellies so I ignore it. After a short time though, my refuse pile starts filling up with wildlife. Turns out the nauseating slime is so nauseating that living things puke so much they suffocate, within a day or two of entering the map. The map was split between two biomes so only part of it was getting slimed, but with critters tracking it everywhere, the whole map quickly turned green.
I had 0 combat units on this map. No traps at all. Each year I was raking in over 100 kills. This goop would kill anything on the ground on contact, it would swat birds out of the sky, nothing was safe, except my undead minions. I had 3 kobold thief groups that I noticed and one elven ambush attack. I only noticed them when their corpses flowed into my corpse stockpiles for butchering. The slime was killing them before any of my units could even encounter them.
It was warlock fortress on super easy mode. The only losses I suffered where from a few harpies that flew in during a break in the goop rain, and a siege where a few members managed to reach my skellies before suffocating. Corpses were effectively infinite, my industrial choke-point was on how fast my skellies could butcher them and churn out hourglasses. I had 30 skellies running non-stop just trying to process all these corpses. 10k meat within 3 years for 0 effort.
Notice the odd bit in there? Skellies butchering. Why not ghouls? Because apparently ghouls can suffocate, they died just like all living things that entered the map. Restless Walker zombies out of the graveyard too. Ghouls I can kind of understand needing to breathe, they even have a thing about their breath reeking of carrion in their description IIRC, but zombies? I ended up ditching the fort because it was too easy. So if you want to play warlocks on easy mode, just find a zone with lethal weather.
Second fort was standard. I just want to mention it because of the zombies again. I actually created a zombie loyalty cascade. Turns out, if you create a skeleton, for a few seconds its considered alive and zombies will attack it. They got a few blows in on the first skellie i built and proceeded to slaughter each other in a loyalty cascade between opposes life units. Zombies are kind of pathetic in combat, die to pretty much anything(during the cascade several zombies managed to wound each other and then bleed to death, zombies bleeding to death), and kill my prisoners. The only real bonus is that when they die, you can butcher them for a lot more than it cost to attract them.
I love the warlocks, they are incredibly fun to play as. But the zombies summoned from the graveyard are more like farmable undead cows than actual combat anything. Their only real strength is their absurd speed.