Or only when he installs a new card over it?

For example, in the last game I played an ovious trap in a new remote server, and put on ice on it. Then later the runner exposed it, and then used bank job on it twice. Could I have just discarded the asset, or do I have to play a new ice/asset/agenda/etc to the server to do this?

Sorry, should read 'no' ice on it.

You can only overwrite it when installing a new card in the server.

Ditto for the Runner. She can only trash programs when installing a new program and trashing hardware or resources requires a card effect to do so. So, if Kate gets tired of going to Wyldside, too bad.

When the corp chooses the install action, they always have the option of first trashing any installed cards in that server before placing the new one. It's explicitly stated in the rulebook, look for the section on installing cards.

OK thanks.

And yes, I did read that section in the rule book first.

My question was whether the act of discarding installed cards in a server was ONLY available when installing new cards.

daleth said:

Yes. Nowhere else in the rules does it say anything about doing that at any other time. I have quoted the relevant section from the rulebook below:

"When installing a card in a server, the Corporation can first trash any cards already installed in that server . Trashed cards go to Archives faceup if they are rezzed, and facedown if they are unrezzed. "

Note that this does not let you trash ice when installing a card in a server or cards in a server when installing ice. You can only trash ice when installing ice on the same server and trash cards in a server when installing other cards in that server.

Khudzlin said:

I'm new to the game, and what you said makes me curious. Is there strategic value to trashing ice?

Installing a piece of ice costs as many credits as there are ice protecting the server already. By trashing ice, you reduce that cost. If a piece of ice is going to be trashed because of parasite or is too cheap for the runner to pass (like Enigma vs Yog), you might as well save the credits.

I was caught off guard by this situation during my first game too, since the game mechanic is implied. I arrived at the same conclusion Toqtamish described from a different angle:

The situation is that an Ambush Asset is essentially a "1-shot" type of card. Once the runner exposes it (or accesses it but does not trash it), the card does not automatically discarded, but remains in place in its original state.

This implies that it is up to the Corp player to trash the stale Ambush card to replace it with a new card that will be useful again. Otherwise the Hacker will likely ignore that server for the remainder of the game, which could be fine for the Corp player too, if he is not interested in using that server any further.

Well, with Ambush, there's not necessarily any reason to trash it (or leave it, as you said) unless you're going to install something new in the server, anyway, at which point you can then discard it.

In fact, there's value in not trashing an Ambush Asset when you access it. It is now a known quantity, and useless to the corp. If you trash it, it goes into their archives, from which it might be retrieved by other card effects and cause you headache in the future.

There's a similarly minor value to the corp in not trashing a known trap asset. If you're trying to build a solid data fort for a fast advance with SanSan, for example, that 3x advanced Junebug is a wonderful deterrent from the runner coming in and trashing your upgrade while you build up the ICE and wait to draw an agenda to put there.

Generally speaking if you are the runner it is a good idea to trash any ambush assets that you access which have advancement tokens on them. Otherwise the corporation has the option at a later time to move those advancement counters to a piece of ice agenda or other ambush asset with trick of light