Tanks do their job well, but they're not the only ones that can herd. In fact, I would say debuff herding is more effective and powerful than any other kind. Here's a video demonstrating the technique with a Dark/Dark Corruptor, but the same method will work for other sets as long as you have:

1) Stealth
2) A "droppable" slow power
3) Some kind of crowd control/damage/accuracy debuff