Subliminal Messaging is an interesting card that does a lot of different things, and its main focus – and use in a deck – has shifted around over time.
As an economy card
The most obvious use of Subliminal Messaging is as an economy card that gives you 1 every turn the Runner doesn't run (but that doesn't work as well in multiples). This can be a pretty good rate of return, if you can set your deck up in such a way that you can penalise the Runner for running a lot. Against many decks, most Runners will run most turns anyway, so Subliminal works best in cases where they don't. The key thing to notice is that a single copy of Subliminal doesn't cost you a server, or an install click, or a rez cost – all you need to do is draw it and it'll be ready to make money right away. The fact that it gives you a 1 bonus on the turn you drew it, even if the Runner ran last turn, helps to blunt the cost of the card (one card is worth more than 1 but not by that much). It does cost a deck slot, though, which means that it normally isn't worth playing Subliminal unless it's a particularly good fit for your deck.
As such, generally speaking, Subliminal Messaging as a pure economy event works best in pure glacier decks; standard strategy against those doesn't include running every turn, so you're likely to get the free credit quite frequently. Non-glacier decks face the issue that many runners (Hoshiko, Sunny, Smoke, Freedom, and most Criminals) get enough value from the fact of having made a run that they will naturally want to run pretty much every turn, if there's anywhere they can get in (and sometimes even if there isn't) – only glacier decks are likely to be able to ICE up everything to the extent that "value runs" become worthless.
As a combo card
Despite its obvious use being as a source of economy, Subliminal Messaging also started finding its way into combo decks. This is based on the fact that it's an operation that refunds when played – these decks mostly don't care about the 1 economy, but purely about the fact that the operation refunds itself. In particular, a copy of Subliminal was standard in Accelerated Diagnostics decks, back when they were legal – if you can hit Subliminal Messaging off Accelerated Diagnostics, you just refunded the click (and credit!) cost of the Diagnostics. Accelerated Diagnostics' best friend Power Shutdown also combos somewhat with Subliminal Messaging, in that the run that turns Subliminal off turns Shutdown on.
The Power Shutdown/Accelerated Diagnostics combo is behind us, and that's probably for the best – it's banned in everything (even Eternal, a format which only has four banned cards). The "Subliminal click" lives on, though, in the form of MirrorMorph: Endless Iteration. MirrorMorph's ability gives you a bonus click as long as your first four actions are all different, but it doesn't care about actions beyond the fourth. This means that in a MirrorMorph deck, Subliminal Messaging can be used for "click laundering", counting as a "play operation" action without actually spending a click, and serving as one of the simplest ways to get a five-click turn (thus allowing you to play two duplicate actions, as nothing stops the fifth action being the same as an earlier action). An extreme example of this is when you have a Bass CH1R180G4 pre-installed; you can 1) install an agenda, 2) play Subliminal, 3) pop Bass, 4) advance the agenda, and now that you've satisfied the MirrorMorph trigger the 5th, 6th and 7th clicks of your turn can all be advances, making it possible to score a 4/2 from hand. A preinstalled Bass can normally only score 3/2s, but the Subliminal Messaging managed to smuggle an extra click past MirrorMorph's trigger.
As an amplifier for Jinteki economy cards
Subliminal Messaging, when played, gives 1. However, you don't necessarily have to play it immediately after it comes back to your hand, and this turns out to give synergy with some of the Jinteki economy cards. There are two really big synergies which mean that Subliminal Messaging can easily earn a spot in JInteki decks that run operation economies:
- Subliminal Messaging can be discarded to Hansei Review, and yet you didn't really lose a card in the process (just 1 because you discarded the Subliminal rather than playing it). This removes Hansei Review's disadvantage over Hedge Fund. Admittedly, it also removes the advantage, but hey, it isn't like Hedge Fund is a bad card – most decks that play an operation economy would be happy to play six.
- Subliminal Messaging can be revealed to Celebrity Gift, and you still get to play the Subliminal Messaging afterwards. This helps to blunt Celebrity Gift's downside; if your hand is full of Subliminal Messagings that the Runner knows is there, you can just show them to avoid having to show something more important. Especially if running multiple Subliminals, it's quite common to be able to hide a card or two from the Runner and yet still get the full value of your Gift.
Hansei Review and Celebrity Gift are probably the top two Jinteki economy cards at the moment (if building a Jinteki deck that can't use an asset economy, and most of them can't, those are the main Jinteki cards I would consider for its economy – most of the best economy cards are neutral). So Subliminal Messaging being able to combo with both of them is something that really pushes up its value, and helps to make Jinteki as a whole a more viable faction.
There are other Jinteki cards that like Subliminal Messaging, too (e.g. Genotyping and particularly Hyoubu Institute: Absolute Clarity), but they aren't as good or as commonly played. The Review and Gift synergies are easily good enough to give Subliminal a slot in the typical Jinteki deck, though.
As protection for HQ
Sabotage is one of the new abilities in Midnight Sun; it's one of the more popular deck styles in Startup, and people are experimenting with it in Standard too. If you're up against Esâ Afontov: Eco-Insurrectionist, then having a card that you can cheaply discard from HQ and bring back later is very valuable; as such, Subliminal makes for a particularly good discard to sabotages. Once you find the Subliminal, it effectively forces Esâ to run every turn, or else have half of xir deck switched off. Esâ decks are generally set up to be able to do that if necessary, but you're still cutting down the Runner's options, and slowing down their setup; Subliminal Messaging helps to fight those decks by forcing them to spend clicks running rather than giving them the option to take turns fixing their economy. (The same idea can also be used against Alice Merchant: Clan Agitator, who doesn't technically sabotage, but whose ability is very similar.)
Subliminal Messaging is an untrashable operation, too, so it provides some protection even against more normal Runner playstyles; HQ accesses hit random cards, and Subliminal can be one of these cards. Admittedly, you could use almost any ICE or operation for that, but Subliminal goes into an economy slot (so it's helping to move your economy card mix more towards operations, which is a good thing in terms of HQ protection), and it partially works around the main downside of running lots of operations: operations tend to clog your hand if you can't play them immediately, but there isn't any cost to "discarding" one Subliminal per turn (by playing it) and it tends to come back on its own later on, when you might have more room in your hand.
Subliminal Messaging might at first seem to be an economy card, but it's also a combo card – and in Jinteki decks running an operation economy, a better economy card – and tech against sabotage – and a little bit of HQ/R&D reinforcement. That's a lot of jobs that one card can be doing, but they're all kind-of minor, and all of them get affected if you're allowing the Runner to run every turn and get most of the benefit of their click. If you can make (or if your deck naturally makes) running costly for the Runner, though, it isn't rare for a copy to pull its weight economically over the course of the game; it'd be a decent economy operation even if it returns to hand only twice over the course of the game (that would be a clickless 3, which is up there with the premium Corp economy cards). It is, however, at its best if your deck can also do something else with it; if you're running Celebrity Gift and Hansei Review, or if you have a combo that benefits from the click, or if your deck is weak to sabotage, then it really starts showing its value (often even to the point that playing multiple copies becomes worthwhile). But if you're playing the sort of deck where the Runner will want to run every turn anyway, then your Subliminal is worse than useless; it's rarely worth spending a card to gain 1, not even when you can make the trade clicklessly, and yet if you never get to bring it back, your Subliminal will never get to do anything else.