I have a question about the stand your ground card, it says:

Action: Put into play one target Dwarf unit that entered your discard pile this turn. (You choose the zone in which the unit enters play.)

Does this work if the dwarf unit card was played as a Developement ? I would say no since it wasn't a Dwarf unit the time it entered the discard pile, it was a Develeopment, but I can easily imagine it the other way.

Moved in the discard pile it loses the development state and so it is a unit that entered the discard pile that turn. I would allow it.

Yep, totally legal. The cards have no memory about its previous states which is also why when it comes back it would be with zero damage if it had been a unit that was destroyed. The checks the card makes are as follows -

1. Does the target card have the Dwarf loyalty symbol?
2. Is the card a unit?
3. Did it enter the discard pile this turn?

If all four of those checks come out as valid then the card can be put into play into the zone of your choice (barring restrictions on the Dwarf unit itself about what zone it may be put into, and assuming it is not a hero being put into play in the same zone as another hero).

Thanks for your answers.

I assumed so, but I would have been clearer for me if the card would have stated Dwarf unit card.

But in that case, what is with the dwarf ranger, does he trigger if a Development which is a Dwarf unit leaves play ? I would say no since he is still a Developement when he levaes play ?