Naggaroth Spearmen

Dark Elf: Cost 3 (with 2 icons needed)
Battlefield ACTION: Spend X resources to have this unit deal +X Damage in combat until the end of the turn. X is the number of development cards in this zone.

Destros TRUE bolt thrower?

Whip the Slaves / Lash the prisoner!

both say "Sacrifice a unit to..." they dont say "that you control" soo can i pop the other guys stuff?

going for my "master of the dark elfs" AP at locals.. fun stuff

Naggaroth Spearmen are indeed a good unit, and they are similar in a sense to bolt thrower in the way you pay for extra damage (i.e they like bolt thrower can activate there action many times with 1 development to continually increase there combat power)

However being a unit changes things dramatically, there are lot more cards that kill units in various ways than supports, there is also the fact you have to attack with the spearmen meaning your open to getting killed in combat or by counterstrike damage.

I personally feel the unit has more in common with greyseer thanqoul, but instead of needing lots of skaven you need a strong resource engine. The unit can work very well as dark elves do possess probably the best ways of getting rid of pesky defending unit.

As to the sacrifice question, unfortunately you can only sacrifice your own units, I believe it is in the rulebook or in the warhammer invasion errata/faq.

From the FAQ:

Sacrifice
Sacrifice means to put a card that you control into its owner’s discard pile. It cannot be cancelled or prevented by other effects.

Even ignoring that you can only sacrifice your own units, that it is a "do [blank] to do [blank]" format means it is a cost for the effect and costs can only ever be paid with your own cards/resources otherwise what is to prevent you from reaching across and using resources of your opponents to pay for your card effects?

It is all the same thing.

thanks for the FAQ, looks like ill just have to run 3 of that grabing spell.. and alot of MC stuff.. god i cant wate for slave pens