me and one of my friend was playng against each others in a "frendly" tournament.

i've already scored "House of Knives" agenda, and i have an agenda counter on it.

i've also have a remote server with a non-rezed ice, a Shock! asset as a trap, and the "Hokusai grid" upgrade, already revealed.

In my friends tunr, he was making a run, He bypass my ice (a paper wall), And declare "i'm now accessing that card"(the Shock! trap)

At that point i've stopped him sayng " first you make a succeful run, so first you will take the "Hokusai grid" net damage. And he agreed

so again he said "now i'm accessing the card", and he start flipping, than i stopped him declaring, "there was a shock! and i'm gonna use my agenda counter from "House of Knife"

he had enough card, and click left so i want to do as much net damage as possible to force him to waste his Click later

but here he said "No, i'm not accessing it anymore" and i was like "what do you mean? you see there is a shock,! but because you say you want to access it, now you HAVE to"

And he replies "no i have not, you make me a net damage with" house of Knives" and now is too risky for me, so i dont want too".

now i'll make a -long story short-: we start yelling about "you declare 3 times you are accessing my card, now you see there was a shok! so you're a tring to cheat in order to not take the net damage! " - "no i'm not, i can retreat anytime i want, it was your fault telling me there are a shock! too soon"

so, ignoring the childish part i want to know 2 thing:

First: he's right? he can really declare to accessing card and at last second just say no? maybe i declare too soon what that card was, but since he said "i access it" i really dont see why i should not tell him what was under.

second: can i use (in this istance) "house of Knives" agenda counter AFTER somebody access any card during a run? My friend say no, because accessing a card end a run, but i'm not sure about it.

Check the timing chart in the FAQ. The runner decides to continue into the server at step 4.2. This is the last time they can Jack out.

At step 4.3 you can use paid abilities like House of Knives, this is the last time either player can use laid abilities.

At step 4.4 the run is successful so now Hokusai Grid triggers at step 4.4.

And finally at step 4.5 the runner MUST access cards to takes the damage from Shock!.

To summarize to your situation:

4.2. Runner decides to continue

4.3. Use HoK to deal 1 net damage

4.4. Run is successful and Hokusai deals 1 net damage

4.5. Shock! Is accessed and deals 1 damage. Hokusai is also accessed and can be trashed.

You were correct (but had the order of events wrong), opponent was wrong.

After passing the last piece of ICE, the runner gets a last opportunity to jack out. If he doesn't, there is a window to use paid abilities (such as House of Knives), then the run is declared successful (at which point Hokusai Grid should trigger) and then he accesses cards. He can't change his mind about accessing, and you can use House of Knives after he has decided to access but not after actually accessing.

Sorry for double post. But another point. The runner CAN'T Jack out whenever they want. You also CAN'T use House of Knives whenever you want.

Download the FAQ ad memorize the timing chart on the last two pages.