Yaotl

I think a good use of this card could be with Agnes Baker or on another level with Patrice Hathaway. Combined with Scrying or Scrying(3), you can see 3 cards of your deck, and decide to discard the one you want, especially Treachery Cards. Moreover, correct me if I'm wrong, but Patrice Hathaway can choose the order of the cards in her discarded hand, making Yaotl sensibly more powerful.

That she can. There are two big issues with this. First, Yaotl doesn't count wild icons, which unfortunately are Patrice's bread and butter. Secondly, Patrice is already pretty happy with some very specific allies. Madame Labranche is insanely good for her combined with her Violin to help her pay for anything she happens to draw (or to sink into Fire Axe tests). Peter Sylvestre 2 buffs her Willpower, which is her most tested skill. Miss Doyle allows her to change her base stats to 5 and has a lot more control in a Patrice deck where you can quickly discard one cat to draw another one from your discard pile. Soon we'll also have Summoned Hound which is potentially an extra action every round for Patrice, which is massive as her current issue right now is not her inability to test well (wild icons, Cornered, Recall the Future, etc already have her covered there) but actions. — StyxTBeuford · 13049
Otherworld Codex

Wow! Most tomes are only good for investigators whose names rhyme with Crazy Stalker -- but this might be the rare exception. Assuming I read this right, you peruse the top nine cards of the encounter deck, choose one, and then discard a copy of that card that is currently in play. In other words, if there's a conglomeration of spheres squelching around your map, and you find his twin brother in your 9-card draw, you can discard said conglomeration. Or if someone has a hex or a miserable Frozen in Fear in their threat area, and you find the match, you can discard that too.

This is impressive versatility! Each time you crack your codex, you have a decent chance of discarding literally any non-elite encounter card currently befouling your board -- whether it's an enemy or some treachery, whether it's at a location, in your threat area, or attached to the act or agenda deck.

Let's think about this. We have some cards that let us discard enemies, like the Disc of Itzamna, or Persuasion. We have a couple that can cleanse your threat area -- Logical Reasoning and the very fancy Cheat Death, which you'd only use in an extreme situation. I don't know of any player card that can pick off cards attached to the agenda deck. And here comes this codex that can do all three! All three three times!

Of course, the the codex does come with some chanciness. You may not find the duplicate you were hoping for in your 9-card draw. If there are only a couple encounter cards on the board, you might whiff altogether. The codex gets better and better as the encounter deck dwindles, and as encounter cards start to pile up on the board. It depends on the scenario, but it seems to me that in a three-player game, it doesn't take long for the board to start filling up, and thus for the codex to become reliably useful. If you play it with 3 or 4 encounter cards on the board and 20-25 in the deck, you'll probably get to discard something, even if not your first choice.

So who should take it? In my view, anyone who can... As with all tomes, Daisy can use the action for free -- always nice. Mandy can potentially discard TWO cards from play, which sounds amazing. But really, I think it's great for any investigator. Joe and Roland might prefer to keep their hands free for weapons, but sheesh, the codex can be a pretty dang good weapon in its own right!

If you want to make the Codex a key part of your deck, consider including means of extending its usefulness as well. You might take Astounding Revelation, which will let you add secrets to it, or Knowledge is Power, which will let you use the Codex without burning a secret. For an item this good, it's worth eking as many applications from it as you can!

It is so so swingy based on scenario though. Fate of all Fools in play? This card can wipe out like 3 encounter cards worth of badness in one go. A set with a lot of hidden and revelation cards? Nope you’re outta luck. It’s definitely scaled better to TCU and much worse in Carcosa — Difrakt · 1319
Anyone who can? As in every Seeker or Sub Seeker should take this card? I havent used it myself, but for such a swingy effect that mostly only effects enemies anyway, it seems to me you’re better off saving the hand slots and should just use Ive Got a Plan or Disc instead. Heck, if you want the best enemy mitigation Seeker card in the game, you can pay 1 less XP for Pendant of the Queen which also works on Elites. — StyxTBeuford · 13049
Id also add Roland hates this as a weapon, since discard is not defeat, so he gets nothing from his ability by triggering this. — StyxTBeuford · 13049
Alter Fate can also discard treacheries attached to acts or agendas — Yenreb · 15
I don't really think Pendant is a fair comparison. It's great for keeping a boss evade-locked or something, but doesn't help you much with cultists. Disc of Itzamna would help you with something like a Brotherhood Cultist, but not so much with the Dark Cult. Also it's a one-time effect if you aren't Scavenging it. — Zinjanthropus · 229
"Let God sort them out..."

Ah, bonus experience. People will do crazy things from bonus experience. They might drive themselves insane with Arcane Research, risk catastrophe for everybody from Delve Too Deep or show off their death wish with Charon's Obol. However, how possible is it for someone to slay a giant pile of monsters?

The first and most obvious caveat is that you have to be a monster hunter to hope make this work, and that you must also have access to the Rogue pool. While this is a restriction, it's not one of the heavier ones - a number of rogues can be reasonable monster fighters, and a number of non-rogues have enough access that it's not too hard to add one copy of this.

Second, this means you need to be able to kill 6 HP worth of enemies in one turn. Practically speaking, this generally means that you'll be using it after either finishing off a single large enemy, or a pair of decently chunky enemies. This ends up being a more notable restriction. In smaller games, this is only likely to happen in very specific circumstances. In solo, the only way you'll have 6 health worth of monsters in one turn is if you've had a particularly rough set of turns and failed to finish off a monster along the way, both of which mean you're already in a less than ideal position. In two player, it will require appropriate setup, since a teammate might leave a hunter in place and you can try to arrange for it to approach. It's when you hit three investigators that this becomes merely 'unlikely' - it becomes more plausible that you see multiple monsters. Some guardian tools like First Watch or On the Hunt help to find monsters, while Dynamite Blast can often kill them.

(The primary exception to this is if you're about to hit a scenario where you know an elite monster is coming up, and you want to get into a slugging contest with it. In solo games, elite health might end up on a borderline. However, in two or more player games, elite monsters almost always have enough health that you can try to finish one off.)

Third, in scenarios where you can't finish something off, this is only worth a single symbol when committed. It's a very weak commit option, so you'll only want to include it if you're fairly sure you can use it.

Fourth, it's worth noting the card itself is not fast and ends your turn. For most characters, this means that your final action must be spent to actually play the card. This gives you all of two actions to obtain the required kills, unless you're using Leo De Luca or have some other method of obtaining bonus actions. It also means that you won't be managing two copies unless you manage a second unlikely fight on top of the first unlikely one.

Finally, it's worth noting that the net result of your setup and sacrificed card and action, the reward for this is a single XP for one investigator. All of those conditions end up only helping a single person. This usually means that your entire team needed to coordinate to set this up, and the result is that you spend a single action and card to get a single XP for yourself. Is that much effort going to be any more possible than gaining another XP for the entire group for meeting another victory condition? More often than not, I think the group would rather go for another victory point outright.

With so many different restraining conditions, is this worth it? I think one copy could be playable in a few very specific characters or swapped in with Adaptable when you know there's a good elite target coming up. If a fight occurs in the first mission of the campaign, you might also be able to put it in your initial deck and replace it early. Otherwise, this card is too inconsistent to be worth the card slot. XP is valuable, but I don't think a few bonus XP for one investigator is worth permanently forcing your entire group to play awkwardly and the dead draw it would otherwise represent.

(TL;DR: Probably not worth it. Use Adaptable for elite fights or drop it early. Only leave it in if you're an extremely focused monster fighter in a larger player count game.)

Ruduen · 1015
Worth noting that it’s a Tactic for Mark/Leo to put on Stick to the Plan. — StyxTBeuford · 13049
There are some non-Elite 6 health baddies in some scenarios. Even in solo, if you're going to face down spheres or vines, you might as well get an extra VP out of it. (Except, of course, for all of the drawbacks. I haven't played this yet. There was a deck I tried to fit it in, but it didn't make the cut.) — Yenreb · 15
Just played return to Dunwich as Leo and TCU as Tony , this card did its job pretty well. In fact It's way more easier to accomplish this using the Guardian. In early scenarios it's hard to deal 6 damages in 2 actions so you may leave some monsters damaged and collect 6 health for the next round . Later you just fire your customized flamethrower , tap your beat cop , then stick to your plan. As a pure fighter in a 4 players game you won't have much to do After you cleared the board , you deserve your little reward . — Tzolkin1065 · 155
I didn't account for Stick to the Plan during my considerations, and it definitely makes the card feel less 'dead' by removing it from the card pool. I'm not sure that it's worth slotting in more than other cards, though. — Ruduen · 1015
I don't remember encountering a lot of high HP non-elites, so I'd need to check which particular encounter sets/scenarios they're in. That being said, they probably fall under the same category as elites - 'worth it if you know they're coming up or have adaptable'. Noted, if you're in a campaign where they always pop out, that also makes it much more reasonable to leave it in. And yep, a pure fighter in a 4 player game will have a much easier time triggering this. There's a reason I have that caveat is in the TL;DR. — Ruduen · 1015
You have to really already be cleaning out the Victory Points in a scenario for this card to be of any real value, but it sure as heck is fun to try to set up and satisfying to see go off. — Death by Chocolate · 1489
It looks bad when your investigators kill an enemy in handcuffs but enemy management cards that leave them on the board gain a bit more value with this card. The new bolas and handcuffs can help you keep one or two chumps around until there is enough enemy health to pull the trigger and "let god sort them out". — techoatmeal · 15
Quick addition to the Tactic/Fast aspect: Chuck Fergus helps a lot to make this work. — AlderSign · 391
Do you have to actually deal damage worth 6 points during that turn, or is it enough to finish off one or two enemies who originally had a total of 6 health? — Krozam · 1
You just need to defeat enemies whose total health is 6. So if a boss with 12 health had 11 damage on it, dealing that point of damage by itself would trigger this card. — Cassus · 35
Luke Robinson

Luke Robinson is a pure mess of an investigator as it currently stand, everyone has their own interpretation of how his effect of playing events as if being at a connection location actually works.

So until some FAQ on him is released I would say he is close to unplayable, you will be making up rules and spending insane amount of time trying to read the current rules to determine how his ability interact with them or reading conflicting intetperetations of how his ability works in given situations on both reddit, BBG and other places . Being consistent with what ever rulings you might come up I personally found to be extremely hard.

Some questions can be answered, but others like what happens to enemies already or becoming engaged with Luke during the event work when played at a connecting location work? - there are no clear answers in the rule book, under Engagement it only talk about enemies in the Threat area when moving, so what happens when you are not really moving but are just there as if. Do they follow you or disengage? - What if they already are engaged with you when you play the event - you are considered to be as if your are at the connecting location when playing the event so did the already engaged enemy "follow" you? or do they disengage and reengage? Do they do Attack of Opportunity?

tdctaz · 48
I am playing true solo Luke in the dream eaters. For the time being I had zero issues in deciphering what should happen. there can be problematic cases but in actual practice I have been enjoying the experience. — Lord Phrank · 76
You're not actually engaged with them, so none of that movement stuff applies and neither does it trigger any AoO. This is really not that difficult to understand. I'm pretty sure the 'as if you were engaged' thing is just intended to allow certain events which require you to be engaged to function. There aren't many of these atm, but we don't know what might be coming down the track. — Sassenach · 180
I played him true solo as well and ran into no issues. Most of these FAQ matter more in multiplayer situations. — StyxTBeuford · 13049
I played him in 3 player and also think he needs some clarification, like: Where do other players need to be to commit cards to his ability? What investigators take damage from his storm of spirits (and symbol is drawn)? While playing a clue event, can he play fast events at the other location like crack the case? — Django · 5154
You are effectively engaged though, so I think it absolutely should trigger AoOs from the enemies at the event location. You 'play [the] event... as if you were... engaged with each enemy.' Part of playing events (or assets) while engaged is triggering AoOs. I'm just not sure about enemies at his original location - I've never used his ability in such a spot yet, but I reasonably could at some point. — Death by Chocolate · 1489
For the most part, looking at the wording, I believe the condition of "You may play one event each turn as if you were at a connecting location and engaged with each enemy at that location" applies directly to the activation of the event itself. Or at least that's how I would interpret it. If they wanted it to be something where you could play an event and invoke AoO, then I distinctly feel they would of clarified such in the text of Luke's card. So, for all intents and purposes, he is at his location except in regards to where the game considers he activated the event. I dunno, it's pretty much up to player interpretation. — WolfGeneral349 · 12
You have "no problems" with Luke Robinson only if you take a habit of "shortcutting" the potential problems. For me he was pretty much problematic as soon as I started using him. What happens if I play Shortcut? Does this mean I can jump from an unrevealed location to an even further unrevealed location? What happens with Barricade? Does it whiff immediately or does it stay permanently until an investigator enters again and leaves? Is he getting AoOs or not (the community is firmly split down a middle on this one)? He is pretty much "still in beta", and a real headache to play if you care about playing by the officially sanctioned rules. — ratnip · 68
A lot of those I'm fairly sure we know how they resolve. Shortcut basically works as a double move. Barricade stays where it's played and does not whiff because you never entered or left the location, you merely played it as if you were there. The AoO one is the toughest one but in solo it was not problematic, and for now you can grim rule it. — StyxTBeuford · 13049
There shouldn't be an AoO, since playing an event doesn't trigger an AoO, spending the action that allows you to play an event does. Since you spend the action first and then the playing the event happens, there is no AoO. The situation perhaps gets a bit messier if you're somehow taking actions during the resolution of the event, but I can't think of a situation where that would happen. — Chitinid · 14
Edit: Never mind, FAQ says otherwise on the AoO — Chitinid · 14