The obvious use of this is to dump agendas from a flood. They will be incredibly safe in most cases. Perhaps put this on your scoring server, or an econ server, or R&D, whatever. Somewhere they have to run. Then they have to choose whether to pay the insane 5 trash cost, or have it trigger every time they run that server.

Or, they might just access it naturally in R&D, HQ or even Archives. Perhaps you fake-out a dump of agendas, and stack it with lots of face-down non-agenda cards, including this, then tuck the agendas that are in your hand when they run archives. Or put it on HQ, so when they run to steal agendas from hand, they only get to access once before you tuck the rest.

That's all well and good. What really excites me about this card is its potential in Cerebral Imaging: Infinite Frontiers, for the Power Shutdown/Accelerated Diagnostics combo. (If you're unfamiliar, it's a deck designed specifically to trash all of R&D with Power Shutdown, then play Accelerated Diagnostics repeatedly until it wins you the game either by fast advancing agendas or killing the runner.)

A problem that deck often encounters is having certain cards in hand when it wants them in archives, to put back into the deck in a particular way with Jackson Howard after Power Shutdown. Normally, you overdraw, then toss them in archives, or play Reuse. But Disposable HQ doesn't just throw them in archives. It lets you reliably stack the bottom of the deck exactly how you want it. Instead of trashing your entire deck with Power Shutdown, you trash all the way down to the cards you put on the bottom, in your chosen order. (Be sure to remember how many you put down there!) Then you Accelerated Diagnostics for the top 3. Oh, look at that, the cards are exactly how you wanted them! This card can help you combo off faster against an aggressive runner.

(Edit: Unfortunately, it seems this is too clunky, slow, and not worth the tight influence slot in CI 7 Shutdown. See www.anrnz.com)

All that, for a 1 influence upgrade with a trash cost of 5, that you hardly even care if they even trash it. Does it fit in every deck? No. But it's absolutely useful in the right situation.

I've tried out a few takes on this, but lets start with the concrete:

Obviously, you want to have plenty of currents in your deck so your ability is active as reliably as possible. I think the sweet spot is 5-6. However, if you're hemorrhaging agendas/down on money, you need something to play. You need a current that's free. Targeted Marketing just happens to be free. It's perfect, really, because every time any agenda is stolen (or scored if you have a spare) you get to reset it to a new target, so it's rarely dead. So in my opinion, 2-3 Targeted Marketing is a no-brainer.

The first real choice you make is what non-free current to run. There are a lot of good ones. Cerebral Static completely neuters quite a few decks, but is dead against others. It can make for a good 1-of. Enhanced Login Protocol adds a click tax for their runs, which can combine well with Data Ravens. Housekeeping is another big one, a card-tax for installing, slowing down their development. Surveillance Sweep is an option, but its problem is it requires the deck be built around it.

The type of deck you build is open to interpretation, but one possibility is a rush deck that happens to get to run the most efficient ETR sentry in the game (News Hound). Add in Wraparound/Quandary and you have a triumvirate of cheap ETR, and then mix in ways of tearing down the breakers once they come online (Data Raven + Keegan Lane, Archangel, and/or a destroyer like Grim.)

If you're going Surveillance Sweep, you're probably going more of a taxing route, so you can throw in Troll, a much overlooked ice, resulting in an absurd interaction, an ice with no subroutines that fires a trace that the runner starts. You can also throw in Ash 2X3ZB9CY at insane efficiency, since they have to do the trace first. The main trouble you may find is the cost of maintaining the current as agendas are stolen, leaving you in the vulnerable position of either nerfing your ice/strategy or going broke and it no longer mattering. Also unfortunately, most tracing during a run happens off of unbroken sentries, leading to a lopsided ice distribution.

Who knows what possibilities will open up in the future. This ID is sticking around forever.

In my opinion, this makes a great sidekick for an AI breaker, since it deals with Swordsman for 3, while being useful against both huge sentries and ones with lots of subroutines, when your AI breaker isn't efficient. Komainu for example. The most commonly used ice where Mimic is 2 better are:

• Gutenberg not on R&D
• Neural Katana
• Turnpike

If you're playing in Criminal, you could even stay in faction and add Breach and Peacock to get around Wraparound and Turing, completing your anti-AI-hate suite.

Alternatively, it can serve as a partner for Femme Fatale, which struggles with playing it early (too expensive) and breaking big sentries (too inefficient.) Mongoose to the rescue!

Oh, and they stack. Afraid of 2 Sentries on a server? 2 Mongooses!

With the MWL doubling Eli 1.0's influence cost, Markus suddenly doesn't seem all that bad. The deck that most easily switches to Markus is (IMO) Jinteki: Replicating Perfection, because it works as an outer-taxing barrier on centrals. Sadly, it rez's for 1 more, and has 1 lower strength, but the unique destructive power partly makes up for that. Worst case, it taxes for 1 or Corroder for 2. Best case, it blows something up and ends the run.

There are several problems with this card:

• Unreliable. It might pick ANY card in your deck, including another Windfall, for which you would get zero credits.
• Only works on non-events.
• Only gets you credits. Credits are good. Lots of credits are very good. But... they're an intermediary to winning the game.
• To be regularly useful, it must get you an average of 3 MINIMUM. That means you need to run lots of expensive cards, which means you need lots of economy. However, that economy better not be events, because those each count as 0 against your "average cost". If it gets you less than 4 credits on average, Sure Gamble would certainly be a better choice in a deck stacked with expensive cards.
• The only way of modifying your average cost in-game is somehow filtering out your cheap cards. Replicator or Paige Piper could do that for you, but would be a huge waste if that's their primary purpose.
• Heap manipulation cards are cheap. All of them, as of Data and Destiny, are either events or cheap, just take a look here

So, you're locked into a resource (or maybe Magnum Opus) based economy plus relying on an event to get you money, which gets worse when you play good event economy cards like Sure Gamble, and worse when you play more recursion. Hard to see an upside, no matter which way you look at it.