If i play an action "in response" to my opponent action and it "resolves". Can i play another action "in response" again before my opponent action resolves.

For example, My opponent play flame of Tzeentch on my unit. I play innovation in response to it. I got 4 development in my kingdom. So i wait for it to resolve.

I gain 4 resources and i play Pilgrimage in response to return that unit back to my hand.

It seem to be the only way.

I can't play Pilgrimage in response to my opponent since i don't have enough resources. Else i could have play Innovation on top of the stack of Pilgrimage.

First in, last out.

Opponent plays Flames targeting your unit. In response, you play Innovation to gain resources. Before Flames resolves and when Innovation resolves, you play Pilgrimage using the resources from Innovation to return your unit to you hand. Flames fizzles since it no longer has a valid target.

Sounds about right to me. If you can't do it that way...

Seems like you'd have to play Pilgrimage first, then Innovation so that Innovation resolves first, then Pilgrimage, then Flames. But I'm 90% sure that you can play actions in response to anything even resolution of other actions.

I think the real question is does Flames really fizzle and go to the discard? or can the opponent who cast Flames choose a new target or choose to no longer use the tactics card? If the stack works like M:TG, then it should fizzle to discard.

All costs and all targets/choices must be paid and declared when playing a card . The action chain and responses only delays the resolution of the card, nothing else. As fo right now we have no specific wording in the rules that says we can respond to a chain that is mid resolution. I'd say things are handled in batches rather than a series of new links being able to be added to the chain, until we get clarification. IOW send it to Nate. It makes sense as a mechanic, several other games have it, but not every game using LIFO, and there is nothing in the rules saying this game does. Here is the link to the rules questions page - www.fantasyflightgames.com/edge_faq.asp .