Drawing an enemy into a trap is perfectly fine, but I draw the line at repeatedly hitting the swinging logs with lightning to make them spazz out and mash up everything in the room. That's what I accidentally did, but that's not really the important thing. In the chief's room you can pretty easily kill the enemies on the back ledge without taking any damage by exploiting pathing and line of sight. The chief and the other goblins should be able to get down into the bottom of the room, if not onto the opposite ledge. That way he can at least hit you with ranged attacks.
I find that the shaman will die well enough just by luring him/her into triggering one of the swinging log traps. He/she is quite capable of doing that even if I'm not around, it seems.
The issue with the chief is that the mesh used for that cavern with the two ledges doesn't actually have a path down from the far ledge. As you may have noticed, to get up there you have to go to the far left side and jump/clamber up the series of ledges. This is something the AI is incapable of figuring out - as you will see if you bring a companion. The main problem, I think, is that NPCs and creatures lack the ability to jump.
Having said that, I have seen the chief and his entourage jump down into the pit (or more accurately, fall down into it) to attack something that was down there, such as rats or mudcrabs. Once down there, they are perfectly capable of getting to you.
Eloise