I don't know if it's a bug, but when I go to drop Entangling Trap it sometimes drops it in front of me, to the side of me, etc. Sometimes conveniently right next to a wall where the mobs definitely won't be running as they chase after me.
It should drop right under your feet when you cast it or just in front of you. If i run into a mob and drop it, it places it somewhere, where the mob isn't standing and off to the side.
