...I made 3 traps and they work fairly well, they seem to 'anchor' any NPC that trips it, unless they destroy it... I trapped as a youth, IRL, and you need to 'guide'/funnel them to the device[chokepoint]. I placed mine next to a terrain wall and a pit I dug, kite them all back to this strip area....they seem to get 'caught' by the trap.

Didn't think they were worth it at first, changed my opinion. Haven't even thought of a Ballista yet, from the negative reviews and it takes 3 springs to craft, no brainer...