Nub question O.O

There's a Necromancer quest I have to do to kill the Nightmare in the Catacombs, but there are traps on the floor that kill me if I hit them. I know I'm supposed to have my minions trigger them, but here comes the nub question:

How do I control my minions to go over the trap before me?

There's a corpse after each trap, if you summon a minion it will automatically run towards you and trigger the trap

I thought it would do that to, like in PvP the npc's that are with you go ahead of you, but when I summon my bone fiend it always stays a little behind me.

This stumped me too when I first played GW.
Ellandra is right, though perhaps I can rephrase it.
As you approach each trap, you'll see on the far side of it - the opposite side from you, the corpse of a devourer. Use Animate Bone Horror from your side of the trap, one will be summoned from the corpse on the other side of the trap, and it will run towards you to take up its place, so triggering the trap and dying before it reaches you, leaving the trap deactivated for you to walk across.
See what I mean? =]

But running into the traps and setting them off is so much more fun What I kept doing

But the proper way is to do what they were saying and animate horror