House of sorrow and Creepshow Cassino - when is an action announced?

These are very interesting questions that need answering other questions first:

A.1. Can I play Conditioning during the “as the action is announced” step?
A.2. Can I use Barrens during the “as the action is announced” step?
A.3. Can I use House of Sorrow during the “as the action is announced” step?
A.4. Can Francisco Domingo de Polonia burn 1 blood to get +1 bleed during the “as the action is announced” step of a bleed action?

I couldn't find an explicit rule excerpt to answer of all these questions. (One of) the original ruling that was made about Conditioning is based on the previous version of the rulebook:

6.2. Taking an Action
Any ready untapped minion you control can take an action. The procedure for resolving an action is described in the following sections. Note that action modifiers and reaction cards can be played at any time in this process as appropriate, subject to the restrictions on adding stealth and intercept listed below and the restrictions against the same minion playing the same action modifier or reaction card more than once (see Minion Cards, sec. 1.6.3), and following the same sequencing strictures of all effects (see Sequencing, sec. 1.6.1.6).

The “as appropriate” is vague but the ruling is based on it. This part has disappeared of the new rulebook, so the following rule should be added:

During the “as the action is announced” step, the only action modifiers cards and reaction cards that can be played are those that are only usable during that step (as well as wake cards).

You can also use other effects such as locking The Barrens to discard a card, or locking the House of Sorrow to unlock another card, or burning 1 blood with Francisco Domingo de Polonia to give him +1 bleed. 

Indeed, those three effects cannot be put in two categories, one that would be “appropriate” for the “as the action is announced” step, and the other not (see also the long discussion about which effects and cards are usable during the damage prevention step once Outside the Hourglass is played at superior: www.vekn.net/forum/rules-questions/76197-still-confused-about-multiple-outside-the-hourglasses#83682 )

So:
A.1: no (since it's an action modifier card)
A.2: yes
A.3: yes
A.4: yes (it must be a bleed action since other rules prevent you from adding bleed to a non-bleed action).

Now, we must answer these questions:

B.1. Is “as an undirected action is announced” a trigger regarding the use of Creepshow Casino?
B.2. Is “as action is announced” a trigger?
B.3. Can Creepshow Casino be used twice on the same action (provided it can be unlocked)?
B.4. Can Tower of London be used twice on the same action (provided it can be unlocked)?

There is a ruling about Tower of London preventing it from being used twice after action resolution even if it is unlocked with a House of Sorrow.

The ruling is easier to understand if you drop the “lock to” part of Creepshow Casino and Tower of London. Could they be used twice? No, as the “as an action is announced” and “after resolution” steps are both steps and triggers. Having a condition such as “the action must be undirected” or “the action must require Necromancy” does not change anything.

Since it's a trigger, any effect depending on it can only be used once: Creepshow Casino can only be used once per action, as well as Tower of London (as well as Andre Leroux's ability).

This implies:
B.1: yes
B.2: yes
B.3: no
B.4. no

So:

heltonmatiazi wrote:

I would like to know if its possible to do the following:
1 - announce action (like KRC)
2 - tap creepshow cassino for stealth
3 - tap house of sorrow to untap cassino
4 - tap creepshow cassino again for stealth

No, see B.3.

heltonmatiazi wrote:

The question popped in a discussion in the local playgroup because some people argued that once the action was 'announced' you could not play the cassino effect again, which I don't think that is particularly convincing because as far as I know I can play creepshow, seduction and any other modifiers that say 'only usable as an action is announced' in the same action. 

To summarize: Is there a window for 'when the action is annouced' that ends at an arbitraty point or can I keep playing cards until I'm done and them the action is effectively 'announced' ?

You can play action modifier cards, reaction cards, or use effects during that step until you are done and pass the impulse.
However, this is not what prevents you from using twice the Creepshow Casino (see B.3.)