I just popped in to say how absolutely disgusting this is with Excalibur. No more runs this turn...oh and also if you want to keep THIS run you can say goodbye to your hand. Then it turns out they're running a Shock! and they die hilariously. Or just put a Kakugo behind it for a hard kick-out. Not to mention it's essentially a second copy of the damn thing on a different server...

Unfortunately the really fun places to do this tend to be Jinteki (White Tree, AgInfusion) which is a pretty huge influence hit. AgInfusion especially could be really fun since you can just send them at the Loki server over and over and over and vary which ICE you use with it based on what their current setup is. The White Tree approach is a little more boring...just force them to run the specific central of your choice if they want to see any of your remotes. I guess you could do something like Wormhole or Susanoo-no-Mikoto to try and force them into an Excalibur subroutine, but influence starts tightening up pretty quick.

...also wait, that top ruling means you can use Loki as a repeating trap since the trash effect traps generally come with doesn't happen. There are a few hoops to jump (rez the trap without trashing it, prevent the Runner from running the trap in order to trash it) so this probably all falls into the Grade A Jank bin. Let's have a quick look at all the traps, shall we?

  • Data Mine: One net damage. Meh.

  • Howler: This seems promising...you can spew bioroids everywhere and- oh, wait, the install ability self-references so it won't work. Sad.

  • It's a Trap!: "Trash 1 installed card" tax for each run of the server. Might be alright, but for such an amount of setup this feels lackluster.

  • Kitsune: You can do a stupid Haarpsichord trick where your remote is literally just Loki and you have this stashed somewhere else, then when they try to run it you feed them a low scoring Agenda to protect the higher scoring one currently in the remove. A lot of moving parts, though. As a bonus, if they try to run at Kitsune to get rid of it you can just not choose a card in HQ and Kitsune won't trash, so you can always just do more basic stuff like throwing them at HQ traps.

  • Lab Dog: Trash a hardware every run. Meh. Good chance of whiffing against a number of decks, and even against decks with some hardware the Dog itself would probably do fine.

  • Special Offer: 5 credits per run? It's not terrible, but it's probably not worth the investment either.

  • Universal Connectivity Fee: Now we're talking. It's probably STILL not worth the setup and the requirement to keep your Fee from being trashed, but at least the payoff looks cool: Slap Loki behind Data Raven and the cost to get past Loki is suddenly "all your credits and your entire hand". Ouch. You'd have to dedicate your whole deck to setting this up in a way that's useful, though, and since it falls over to AI that's pretty meh.

  • Whirlpool: If you're triggering this more than once in a game, you're doing it wrong.

Also, am I the only one that noticed that Loki's natural subroutine stops Faust dead in his tracks? That seems kind of neat flavour-wise.

Universal Connectivity Fee shouldn't work. The runner loses 1c if he is NOT tagged and can ignore the sub if he IS tagged, because the self-reference ability doesn't work on Loki. —
And I disagree on the hard stop for Faust. It's a mere 2 cards tax, which should be fine for every Faust deck. The point is, if the runner relies on Faust, he can break Loki no matter what weird ICE you copy. —
I was under the impression the self-reference bit failed and everything else (i.e. the credit loss) succeeded? —
Hard to say. The official FAQ says "If a card copies the text of another card, and the copied text includes a self-reference, the copied text does not function unless it explicitly says so." To me, that says if any subroutine has a self-reference, the entire copy operation fails (which has the virtue of simplicity). Apparently the UFAQ disagrees though. —
Owl

Owl

One of only a few gear check Sentries, and specialized to require the Runner to find two breakers early game to get into a server. Owl's bread-and-butter use case is to install in front of a cheap Code Gate or Barrier, then threaten to get rid of the Runner's Decoder or Fracter if they can't break it. Then they bounce off Vanilla and are sad. Thus they need the Decoder/Fracter AND a Killer in order to get in, and with a total cost of 3 credits to set up and rez everything it's pretty easy to go Owl/Vanilla/Remote face down install and credibly threaten to use Subliminal Messaging to score a 3/2 immediately unless they can find the two breakers they need right away. Or an AI. Either way, this is likely to tax the Runner's economy if they want to close that scoring window before you can use it.

Most competition is situational (News Hound requires a current, Tour Guide requires face-up assets, Dracō requires money...), with the main exception being the 4 credit Rototurret which is much better at demanding a Killer but much worse at gearchecking two breaker types at once. It's also quite a bit more expensive.

The other main use case Owl has is just as a cheap time-waster. If it triggers on facecheck then reinstalling the program will cost the Runner two clicks and probably some money, which is pretty good, and at 2 credits to rez it can trip up Runners who thought they were safe doing exploratory runs without a Killer because you're too poor to rez anything nasty.

All in all I think Owl is pretty good as a gear check Sentry. It doesn't require extra infrastructure to work, only requires the Runner to have a program installed in order to be annoying, it's cheap, and in a deck already relying mostly on gearchecks it can combine with another cheap piece of ICE to create a surprisingly robust lockout in the first couple turns of the game. So if cheap ICE is your bag and you've had trouble rounding out your ICE suite with Sentries in the past, Owl is probably at least worth a look.

It's also in competion with Sapper in Weyland decks, which are some of the more likely candidates for wanting a rushy kind of ice. And for any deck that isn't running on an absolute shoestring Cobra is usually better too. —
Honestly, this ICE IS for absolute shoestring budgets. It's for enabling a double gearcheck at rock bottom cost. On top of this, trash a program subroutines will fail to lock out against Paperclip/Black Orchestra so that's something to consider as well. (Plus Sapper has a trash cost, and no-one likes those) —

At 1 Influence, this seems like it could rapidly get out of hand in the right sort of setup. Imagine hitting Komainu or Brainstorm with this rezzed and active...you can take the damage or pay to give the corp money. Not a great pair of choices, that.

Unfortunately, the effort to set this up is considerable. You need Henry, AND the nasty multisub ICE, AND something like Bandwidth, Data Raven, or Thoth to slap a tag on them before they hit it. You can try and get the Runner tagged before they start the run, but if you can do that you should probably just be focusing on blowing them up instead.

For an even MORE janky fun time, place this upgrade in Chief Slee's server. Now you can get some work done with ETRs instead of them just bouncing off: Do you give Slee 5 counters off the Hive? Do you give the corp 10 credits by paying to break it? Do you do something in between? It's all bad, honestly.

Of course, this is assuming that Henry needs to trigger in order to be effective. In reality, if you put him behind something like a Spiderweb and a Data Raven then either they'll run it and give you the credits you want or they'll not run it and you can score out or whatever it is corps do with servers that aren't being run. He's cheap to rez, so if you're already running both tagging and multisub ICE (sup Muckraker) then you can get a fair bit of mileage if your servers are structured right. I'm not sure how many decks actually want that particular combination of ICE, though. Some kind of weird NBN Glacier variant?

This guy clearly belongs in Acme Consulting decks, along with ice like Data Ward and Hydra. Sadly doesn't combo with Endless EULA. —

Fun toy for Kit, I would think. As though positional ICE needed any more nails in its coffin...

Anyway, if you're using this with Kit then it's guaranteed to work on the first ICE you encounter each turn. This can lead to fun situations like:

  • Bypassing ICE deeper in the server by swapping it with the outermost piece. This requires you to encounter the outermost piece twice...unless you're using Spooned, in which case you can choose the trigger order (as in the Prey ruling above) so that you swap the ICE you just passed deeper into the server you're running, THEN trash it. Net result: The ICE you swapped it with is now behind you and you never even had to touch it. (EDIT: Apparently this doesn't work with Spooned due to trigger timing, so you would need to in fact use Prey itself for it to work)

  • Find a server with a Barrier on the outside, use Surfer to go all the way in, then use Inversificator to put it back on the outside of the server ready for next time! Requires Kit/Paintbrush/Tinkering/Egret, and with the latter two you can do it multiple times in the same turn. As a bonus, you can use this to PUT that weak barrier ICE in position to start with. This is especially fun with Egret because you can just slap that on any weak ICE, put it in front of the server you want into, and go to town.

  • Ruin positional ICE (duh)

  • Stuff things you don't like on servers you don't care about so you don't have to think about them any more.

  • Hit R&D with an Indexing and weaken the ICE on it at the same time, making the follow-up run much easier (see also: Möbius, Medium, and the more general idea of making follow-up runs against the same server cheaper)

  • Swap unrezzed ICE onto the server you're hitting, then Blackmail your way past it either now or later.

  • Swap rezzed ICE onto a server you WANT To hit, then run it knowing there's no nasty surprises waiting for you. (In general this lets you avoid specific pieces of unrezzed ICE for the cost of running and breaking a Code Gate first)

Most of this works without Kit, of course, but it's so much more universally applicable with her and hard to justify the cost without being able to eke out some serious savings in the next few turns after installing. Probably consigned to the jank bin anyway. Still a good fun way to get into servers in style, though.

(EDIT: Comments have pointed out that Adjusted Matrix is helpful in the same way that Kit is, and that multiple copies of Inversificator allow you to use it multiple times per turn! These are both good things to keep in mind)

Another easy solution to use this on non-Code Gates is to host Adjusted Matrix on Inversificator - so instead of making any ICE a Code Gate, just make your Decoder an AI. Probably just as janky, but it could work against ICE with few subroutines. —
You missed a big one: Install more than one Inversificator, and each one can swap one ice per turn! You'll probably need System Seizure, Dedicated Processor, and/or Stimshop, but with three of these out, the corp needs a four-deep server before you even have to whistle for your Egret. —
More seriously, this is one more tool to help Kit shore up her main weakness: needing to find a killer or SMC to run two-deep servers. Its main use is going to be pushing code gates to the back of servers so she can keep running safely once they get two-deep. I actually think this could replace the killer slot in some Kit decks. This could potentially make Kit a lot faster, since she will be able to spend that time and those deckslots on other things. —
I have been using this in Kit and it is a complete beast as the only breaker. Still optimizing, but I think I'll post a decklist soon if I have the time. One clarification on rules which was pointed out to me: You cannot swap the Spooned ice back and effectively skip the next ice, as awesome as this would be. The reason is that unlike Prey, which triggers at the same time as the swap ability on Inversificator (on "pass"), Spooned's trash ability triggers before that, on "break all subroutines". Thus, they are not simultaneous triggers and you don't get to pick the order. Makes me sad, but there you have it. —
How does it work with Inversificator? —

As far as I can tell this isn't so much an FA card as it is something more specific: A win condition in and of itself. Note that once you score it, you can FA two 3/2 agendas using the ability and this is exactly 7 points. It's kind of like the HB AstroTrain, if that required a 5 cost Agenda to get going.

So the deck would contain these, a bunch of 3/2s, and supporting tech with which to score a 5/3. I'm actually legit rubbish at building Corp decks so I'll leave the exact formulation of this as an exercise for the reader.

Since you only need to protect the scoring remote for 1 turn a setup with Howler and Awakening Center plus nasty ice might work. —