Hello everyone,
I would like a clarification about the following game situation:

I play: "Seeking new slaves" on a unit in my opponent's discard pile, he in reply, play: "Iron Discipline" on his unit in the discard pile, is that correct?

Can I play “Action” whose effect also affects units with the status “not in play” even if not specified in the text?

Iron Discipline can't target a unit in the discard pile. Effects can't target cards that are out of play unless the card explicitly says so (like SNS).

Thanks for the reply Entropy42, I agree with you, there is also an official response on this?

If you carefully read the targetting section of the FAQ and rulebook, its in there. The most clear line says something along the lines of "a target can become invalid if it leaves play" Actions check targets when they are initiated, and at resolution. So if out of play cards are illegal targets at resolution, they would also be illegal targets at initiation.

Or the red text from v1.3:

"Unless otherwise stated, a card can only
target cards that are in play." (p. 5)

With in play being one of the zones.

Does Church of Sigmar affects units out of play ? (Discard/Hand)
Whenever your opponent uses an effect that targets one of your units, they must pay an additional resource. It does not matter if the unit is out of play or in play, provided it is being targeted.

Just read the one post above you that Dam posted.

Virgo said:

Church basically "targets" your opponent, and modifies their ability to target cards, which is why it can indirectly affect cards that are out of play.

Thank you so much, for the clarification Entropy42