I think I already know the answer to this but just wanted to check with the powers that be:

Staging Ground's ability let's you 'Deploy' a unit of cost 2 or lower as an action - 'Deploy' means you have to pay the cost, right? It's not a free drop?

The free one is like Elysian Drop Troopers when you "Put it into play", which circumvents the need to pay for it.

Only used Staging Grounds once, but I think I was doing it wrong. Treating it as "Put into play" when it actually says "Deploy", which I didn't notice before (since I wasn't using it before now).

Loving the new AM Warlord, by the way.

- Deployment (as in the Deployment phase) means you have to pay the printed cost of a card in order to put it into play.

- Putting into play is a result of a Deployment cost paid or a result of other Interrupts triggering from certain things that have happend during a game.

- Staging Ground for a lack of better terms 'puts' Ambush on 0, 1 or 2 Costed Army units. Perhaps this helps remembering that a cost still has to be paid.

It's likely you have played Staging Ground wrong, this does not mean the card is not powerfull by any other means. In special when your able to Ambush Snake Bite Thug, Evil Sunz Warbikers or even Mystic Warden you see how great this Support is.