I wonder how it works with action cards. After i use them they still lay on the table, right? or do they enter the discard pile? I mean in the same turn.

Here's an example. I play Judgment of Verena, one of my zones has no developments and i destroy all units and supports in f.e. quest zone. after that i still have 1 gold remaining so i choose to play Huntsman in the quest zone. And now... is the Verena still in play so i must to destroy the huntsman unit as well or i can play this unit because verena is on discard?

There are Actions written in bold, Forced Effects and Constant Effects.

It's in a Rulebook.

Actions resolve after they are played and the end (for example blah blah Verena and Troll Vomit)

Cards with constant effects are played in Action Window but their effects exist until conditions mentioned in a card description, for example Choppa or War Paint.

EDIT: Of course, there are also cards with Action which are described as "until the end of the turn" but I think it's obvious.

pancerek said:

Well, those two you mention are Supports, so you can only play them during the Capital Phase of your turn, not in any Action window.

My fault
But it doesn't change the main clue of my post. Does it?

A tactic is played, and resolved immediately if there are no responses. If there are responses then they are resolved in a Last In First Out manner. The important thing is that a tactic played is not considered in play and its effect only lasts as long as the card says... which for most means it is an immediate effect and then gone. Tactics are only laid out on the table to better facilitate the reading of the card by your opponent, and to remember where in the action chain it lies. Technically the card never enters play.