How did you do? Set up a chain of characters along the path to the Goblin cell, all equipped with the teleport or/and featherdrop spell? Not for the first death knight - that would be a more or less direct port - but for the ones further away?

Or do the death knights follow a fast character up to the point where direct teleport is possible?

I thought of this strategy in my playthroughs but never had the patience to execute - invisible was so much easier.

Regards,
Thorsten