Hey I know that the rule book says not to use expansions (unit cards) for the campaign, but has anyone had good success with doing so? I would like to add some into the mix for the open groups on my next playthrough. Sorry if this has been asked before, the search on my phone through the forums has been pretty exhausting.

You can add them when you start the campaign. But you shouldn't add them midway through.

So I don't see why you shouldn't add villain pack units into open groups (provided you don't have to earn them through side missions).

Well I am talking more like heavy troopers, rodians, etc as standard none gained units.

As long as the Rebels also have access to the Twin Shadows heroes there shouldnt be a problem.

No, I think what he is saying is can you play the campaign through say Story Mission #2 with IA content and then at Side Mission #3 use heavy stormtroopers and tuskens (on desert maps) in the open groups. Perhaps by puting in the upgrade and supply cards, his opponent would not care.

In my games as long as the Rebels had access to the new items and the imperial wasn't changing agendas (just adding the open groups) then I wouldn't have a problem with it.

There's no rule against using figures in any of the campaigns... it just suggests that you finish a current campaign before adding them, so as not to surprise the rebels who may have upgraded because of one expectation and aren't prepared for heavy troopers or Tuskens or whatever. Personally, I will give it a vote at the next mission if they want to allow/forbid the new figures and supply cards (we won't be changing classes or missions). But when you start a new campaign, you can use anything you have available. - The only limitation is the rule that says how many copies of each figure you're limited so, so you can't zerg-rush the map with cheap troopers.

No, I think what he is saying is can you play the campaign through say Story Mission #2 with IA content and then at Side Mission #3 use heavy stormtroopers and tuskens (on desert maps) in the open groups. Perhaps by puting in the upgrade and supply cards, his opponent would not care.

I already said:

But you shouldn't add them midway through.

Can someone explain the difference between adding an expansion unit halfway through and then using it and having an expansion unit and not utilizing it until halfway through?

The difference is the rebel players knowing those units are an option. If you do use them and the Rebels aren't prepared for them, then its their fault for not taking it into account. But if you bring in a unit halfway through that they had no idea existed, then its a tad unfair if they haven't purchased the correct weapons or class skills to counter it.

In most cases I don't think it matters... For example I don't think bringing in heavy troopers is a problem, as they're just heavier hitting troopers. But something like the Tusken Raiders could throw the balance with their weaken ability, since that would be an ability that wasn't around when the players started the campaign. Additionally there's new weapons and items and supply cards and potential allies they couldn't take advantage of when they started off. In other words the imperial player gets the advantage of the expansion, and the rebel players don't.