Killed Black Crawler recently. Top floor is easy with some traps, definitely not a problem. The biggie's lair is where the nightmare is. There the big fucker and two regular ones. It takes a while to spot them even with 13 PER, with 3 - not a fucking chance. More so, as you descend you can't initiate combat due to cooldown, and there's a good chance to be shanked instantly as there's no initiative rolls when you are attacked from stealth and enemies don't subscribe to attack cooldown idea. Bar that, there's one sweet spot right next to the entry point, little bit NW from it: run there, place one trap (works one time in ten, all others you are poisoned before you can do any of that) and wait - it's just one tile, and combination of bear trap, taser and flashbang gives you five turns to remove the fuckers behind the closest one and then work on the trapped fella. Some incendiary can proc fear and give you some more time due to enemy reluctance to get burned. Two traps would be perfect, but I wasn't able to place them.
All of this wouldn't be so egregious, but for some reason Black Crawler has insane Evasion and Dodge skills. Can you imagine several meters big scorpo actually dodging your attacks? I should be harder to miss him actually. All this endeavor was ten time easier with PSI build, where I couldn't miss and didn't bother with any traps altogether.
And for what it's worth? Fucking nothing. No oddities, and trash loot.