most trap skills like for example the “marks” from the necromancer’s staff don’t work on world bosses, turrets or enemy’s that can’t move. Severely limiting the damage you can do during those encounters as only your class skills will work, while you can’t rely on your weapon skills (unless you use other weapons, but I have a full staff build and my staff is the strongest weapon I took time into upgrading, and I don’t intend on switching to a other weapon build simply course the game promised to be fair no mater how you build your character)
tough I have been unable to test it, most likely other skills from other classes that resort to the enemy triggering the skill will most likely also not work on those type’s of enemy’s.