Warden Krieg is not actually placing his traps in his first form.
He does the animation, I see the trap, then it fades to invisible. I have walked over it before and after it fades and nothing happens. No damage, no stun, no sunder.
This is on Veteran difficulty. The only mod I’m using is Rainbow Filter, which I re-installed from clean after downloading the 1.2 patch on steam.