|Card draw simulator|
Odds: 0% – 0% – 0% more
|None. Self-made deck here.|
|Mandy Thompson, the Ambitious Researcher||0||0||1||1.0|
|Mandy - Dream||0||0||0||1.0|
|Heaven holds a place for those who pray||0||0||0||1.0|
|Occult Researcher: A Mandy Standard Deck||0||0||0||1.0|
|Mandy Standalone PtC Finale||0||0||0||1.0|
|Occult Researcher: A Mandy Standard Deck||0||0||0||1.0|
|9xp Mandy excelsior||0||0||0||1.0|
TheBlackHorror · 7185
Occult Researcher: A Mandy Standard Deck
This is the third in my "Standard Deck" series, where I create highly effective taboo-compliant decks for specific investigators, with a focus on the most recent Dream Eater investigators first. These decks are designed for 2 Players with Standard difficulty in mind, and assume you have a current card pool, but also include modifications for 3-4 players. Each deck will highlight the investigator's strengths, including both instructions on how to play the investigator and how to pilot the deck, with the aim of teaching you how they work.
Want to try the new Dream-Eater investigators, but are at a loss and don't know where to start?
Try one of my Standard Decks!
Have an Arkham event coming up and you need to bring a couple of decks, but don't have the time or brain space to build them all?
Try one of my Standard Decks! You can create quick standalone builds by following the Standalone recommendations at the end of each deck guide.
Imagine these as pre-fabricated Arkham Horror LCG decks that you can crack open and start playing with.
Pair with: Monster-Killer
Strengths: Card Tutoring, Investigation
Weaknesses: Low Combat, Basic Weakness Time-Bomb
Modus Operandi: Mandy is not just a quintessential Seeker, she is the quintessential Seeker squared. She excels in seeking out both clues and cards, which make her one of the most powerful investigators in the game.
A of 3 gives Mandy a decent chance of resisting treacheries from the encounter deck, but with a Hawk-Eye Folding Camera or maybe two, she can easily be up to 5, allowing her to shrug off much of what the encounter deck sends at her.
Her 5 is also something to write home about. Even though Mandy' specializes in fetching cards from investigators' decks, she actually does not need any cards in play before she starts investigating. This allows her to start investigating from Turn 1, giving her a huge head start in tempo. Her ability to pull specific cards from her deck bolsters this already quick tempo, making her a powerhouse Seeker.
1 means she will not be doing anything much in the combat department--not even punching a Swarm of Rats, so you might have to rely on her 3 , which isn't too shabby. It's just enough to evade when you have to, and will make you consider cards like Trench Coat if she is going to need to evade and avoid enemies--especially in true solo.
Mandy's Ability & Card Tutoring
Card Tutoring is a term for searching your deck and retrieving specific cards. Mandy's card tutoring talent makes allies like Mr. "Rook" look delicious. However, as I mentioned earlier, Mandy doesn't actually need any cards out to start investigating...so what cards are you even looking for with her ability?!?
Don't fall into the trap of endlessly spending your actions to search for cards, which help you search for cards, which help you search for cards, etc. You're just wasting actions. You want to search for cards that can make a difference!
Mandy's investigator ability has 2 uses, which can be used by either Mandy or another investigator at her location: when she searches, she can either search deeper (3 additional cards), or more (resolve the effect 1 additional time--so draw 2 cards instead of 1). How do you know which option to choose? That's a good question. See below.
(1) Searching Deeper (Search 3 Additional Cards).
This option simply means that if normally you would search 6 cards, you can now search 9. If normally 9, then 12. Etc. It's a great way to bore into your deck to find the cards you really need.
Choose this option when there is a specific card you want to find. Otherwise, if there's nothing you really need, use option #2 (see below).
Remember: other investigators at Mandy's location can use her ability! Most of the time, their searches (such as with Prepared for the Worst) are more important than yours!
(2) Searching More (Resolve 1 Additional Target).
This option means that instead of choosing 1 card with a search effect, such as with Eureka!, you choose 2. That's pretty good! This gives Mandy (and other investigators at her location) filtered card draw.
Choose this option if (a) hitting Shocking Discovery would be highly inconvenient, or (b) there's nothing in particular you need to search for. This becomes additional card draw with the potential to trigger Astounding Revelation and Occult Evidence.
Generally you will be searching deep at first, then switch to searching more once you have the cards you need.
A Note about Card Draw Card draw--especially in Seekers--is a good thing, right? Right?!? It's less good in Mandy, mainly because it means you might end up drawing Astounding Revelation or Occult Evidence (which personally happens to me all the time). Don't shy away from it, by any means, but Mandy is best served by cards that use search effects to gain cards, rather than plain ol' card draw (like with Preposterous Sketches).
Elder Sign Ability ()
You will never be sad when Mandy's Elder Sign ability crops up. At worst, it's just additional card draw--you can even use her investigator ability to search 3 cards and draw 2! At best it's a lifesaver that allows you to search up to 6 cards (when used in conjunction with her investigator ability) and commit the card you find to the test! Wow! This is really just an innate Eureka!, and another reason to ensure Mandy has plenty of good icon cards in her deck.
Investigator Signature Event: Occult Evidence
Mandy's signature card is singularly unique (pun intended) in that its quantity scales with her deck size. She gets 1x @ 30 cards, 2x @ 40 cards, and 3x @50 cards. It's not a fantastic signature card, but it's not bad either. You will know how many copies of Occult Evidence are in your deck at any given time, which allows you to plan to use her search abilities while on a location with a clue. Worst case scenario, if you draw it during upkeep, it's an extra wild icon.
Remember: just because you find a card with a search reaction (such as Occult Evidence and Astounding Revelation) does not mean you have to trigger their reaction ability--that would make it a Forced ability, instead. If you'd rather keep Occult Evidence or Astounding Revelation in your deck, rather than your hand, don't trigger their reaction ability!
Investigator Signature Weakness: Shocking Discovery
As far as signature weaknesses go, this can be pretty rotten when drawn at the worst possible time. But most of the time, it's not all that bad, especially when packing Tooth of Eztlis and Hawk-Eye Folding Cameras, both of which help Mandy shrug off encounter cards. Mystic off-class Mandy has the added boons in the form of Deny Existence and Ward of Protection, which she can use to cancel the worst treacheries drawn by her signature weakness.
IMPORTANT: Cards that search your entire deck literally search your entire deck--the search DOES NOT stop once you find a card you want. This means cards that search your deck (such as Research Librarian and No Stone Unturned) WILL trigger Shocking Discovery if it is in your deck!
I wanted to take a moment to touch on Mandy's off-classes, since both her and Tony's off-class options can be the most exciting AND daunting aspects about them.
Playing Mandy in 2 player? Give Mystic off-class a nod. This deck uses Mystic as an off-class, since it gives her the most all-round versatility, especially with Read the Signs, Ward of Protection, and Deny Existence. With a Hawk-Eye Folding Camera or two and a Tooth of Eztli out, she will be facing encounter cards with 4-6 , 5-7 , and 4 . This allows her to shrug off a lot of encounters and makes her a great target for a rogue player to pitch to using "You handle this one!". She can then use 2x copies of Deny Existence and Ward of Protection to ignore the treacheries she cannot pass. In my experience, this allows her to ignore the encounter deck and just concentrate on grabbing clues.
Playing Mandy solo? You might want to pick Rogue for her off-class. Rogue offers her a lot of enemy avoidance with action compression. Cards like Think on Your Feet and Slip Away let her put a pin in enemies while she zooms around using cards like Shortcut and Elusive (10/10 would recommend) to effortlessly suck up clues. One of your top Rogue picks should always be Quick Thinking. Mandy can commit this to an investigate test and succeed by 2 with ease, allowing her to take an additional action! Also consider the favor cards like Decoy, Small Favor, and Intel Report. The first two allow her to buy her way past enemies, while Intel Report allows her to buy clues from an adjacent location. At worst, each of the favors has 2 icons.
Playing Mandy in 4-player? Consider Survivor, which has the highest clue-potential of any other off-class, if you take Fortuitous Discovery x3, Resourceful x2, Winging It x2, "Look what I found!" x2, and Lucky! x1 (though I would personally go with Lucky! x2 and "Look what I found!" x1). Later on you can upgrade into Sharp Vision x2. Winging It gets shuffled back into her deck, and because of her card-draw, she will see it several times. Don't worry about how to discard it--Mandy often has lots of cards in hand! "Look what I found!" is a little harder to pull off, but not as hard as one might think, especially if she is working at her base 5 . It also has . Lucky! is an all-around great card that can help you with anything. As for Fortuitous Discovery and Resourceful?
Imagine this: you use Mr. "Rook", Eureka!, and maybe even No Stone Unturned to eventually find all 3 copies of Fortuitous Discovery. When you play the 3rd copy, Mandy can nab 3 clues. But if she plays it with Resourceful committed, she can also grab a different copy of Fortuitous Discovery from her discard pile. Meaning, she can play it AGAIN at maximum effectiveness. With 2 copies of Resourceful, this means she can play Fortuitous Discovery at maximum clue potential 3 times!
The other thing that prospective Mandy players puzzle over is her deck size. As a general rule, fewer cards in your deck is better, since this ensures you are more likely to see your best cards and, if you recycle your deck, enables you to see your best cards up to 4 times in a single scenario. Higher card counts dilute the effectiveness of your best cards, especially since you are limited to a maximum limit of 2 for most.
With Mandy's card draw, you will see and find every card in a 30-card deck likely a few times. Go with this deck size if you want to use and reuse specific cards--such as building specifically for the Pendant of the Queen. With Mandy's card draw ability, a measly 30-card deck lets her use, abuse, and reuse powerful cards with limited uses like Mr. "Rook", Fingerprint Kit, and most notably, Pendant of the Queen.
Mandy's search ability and card draw allow her to operate a 40-card deck as easily as another investigator runs a 30-card deck--and better. I personally prefer this deck size, since it gives you the option of including a few more cards than the often-limiting 30-card limit restricts you to. It also gives you the freedom to include a wider range of utility cards than usual. Going with a 40-card deck also gives Mandy 2 copies of Occult Evidence, literally doubling the number of her signature cards in her deck. As a frame of reference, a 40-card Mandy deck will usually draw through her entire deck once in a scenario, and possibly a little more. I mention this because deck size can be an easy way to combat Beyond the Veil. I played this deck in a 4-player Return to Dunwich, and our Guardian player used First Watch to give me ALL of the Beyond the Veils that came up. With a Deny Existence in hand and a sizable deck, it made life much easier for the other investigators.
If you want to include ALL the toys and ALL the cards...go with 50. Mandy still does quite well. However, you will find that you have to include a lot of redundancies, which make that additional 10 card bump up from 50 far less effective than you'd think. You do get 3 copies of Occult Evidence, but it's not reason enough on it's own to go the full 50. With 50 cards, Mandy may almost draw through her entire deck in a single scenario, which means it might be an option you want to consider if taking a non-mystic Mandy through Dunwich as Beyond the Veil protection.
Deck Size: How to Choose?
Choose a 30-Card deck if you want to use, re-use, and abuse a few select cards over and over again, namely Pendant of the Queen, Mr. "Rook", Fingerprint Kit, and Archaic Glyphs. You will cycle through your deck quickly, allowing you to get a second or sometimes even a third pass at your best cards.
Choose a 40-Card deck if you want a larger toolbox with greater versatility. This gives you some breathing space to include extra cards, such as a the in-game mini-quest cards (Archaic Glyphs, Strange Solution, Ancient Stone, etc), as well as more off-class cards. Mandy can handle a 40-card deck as easily as any investigator handles a 30-card deck--and then some.
Choose a 50-Card deck if you want to include everything. I personally don't recommend this, since it dilutes the likelihood of you finding your best cards, such as Mr. "Rook", but Mandy being Mandy, she can still do just fine. Just make sure to include plenty of card draw and icons.
Premise: Use Mandy's search ability to equip her with the cards she needs to investigate at peak level and protect her from the encounter deck.
DECK PILOTING INSTRUCTIONS:
Mulligan and Opening Hand
You want your opening hand to consist of (in this order):
(2) Mr. "Rook"
(3) Crack the Case
(4) Fingerprint Kit
I gave a suggested card order, but really Mandy needs nothing to actually investigate. However, you do want at last one Hawk-Eye Folding Camera out early so you can get it fully charged as quickly as possible. Aside from that, all you really need is Mr. "Rook", who will help Mandy find her other cards.
Crack the Case is an early economy card, which helps you pay for Fingerprint Kit. Tooth of Eztli will help you avoid the encounter deck, while also drawing cards. Eureka! is a skill card that helps Mandy pass tests while also searching for useful cards.
How to Use the Cards in this Deck
This deck gives Mandy a lot of chances to search her deck--a very powerful tool indeed! Just make sure you spend your actions wisely. It's easy to fall into a cycle of searching for cards that search for cards, which search for other cards. This is a waste of actions--so don't do it! Mandy's primary goal is to investigate. You want your actions aimed at grabbing as many clues as possible, whenever possible.
All the cards in this deck focus on helping Mandy investigate efficiently or shrug off the encounter deck, and searching for cards that allow her to do these things. Just be warned: there are a lot of cards with search effects in this deck. Don't fall into the trap of spending all your actions on searching Mandy's deck! Search for what you need to investigate--that's how you win scenarios!
Ideally you want a camera in one hand and a Fingerprint Kit in the other for most of the game.
Fingerprint Kit: This card gives Mandy some clue acceleration, but since it exhausts, it is limited. As mentioned above, ideally you will want a Fingerprint Kit in one hand and a Hawk-Eye Folding Camera in the other for much of the game, especially early on. If you have a Fingerprint Kit kit in play and another one in hand, you can cheese a double-play. On your first action, use the existing Kit's last supply to investigate for +1 Clue, then play the second Fingerprint Kit from hand, bumping the first to the discard pile. Then for your third action, use THAT Kit's ability for another 2 clues! Keep in mind that you can use an upgraded Emergency Cache to add 4 supplies to your Fingerprint Kits.
Hawk-Eye Folding Camera: Mandy only needs one of these in play, especially early on, to leave her other hand free for a Fingerprint Kit or Occult Lexicon. If you've burned through both Kits and the Lexicon, you are welcome to drop your second Hawk-Eye Folding Camera into play. However, you may want to hold it back as insurance against cards like Crypt Chill
Occult Lexicon/Blood-Rite: Occult Lexicon gives Mandy access to Blood-Rite, which grants her 3 very useful options: draw 2 cards, get 2 resources, or deal 2 damage. This kind of versatility allows her to get what she needs most, when she needs it. The 2 testless damage can also be an incredible life-saver, either for you or for a fellow investigator. As long as Shocking Discovery isn't in your deck, you can pull this out of the bottom of your deck with Research Librarian.
Tooth of Eztli: This card gives Mandy valuable defensive boosts to and , and also lets her draw a card when she (usually) passes. One Hawk-Eye Folding Camera and one Tooth of Eztli will let Mandy tests at 5 and 4 , AND draw a card. That's pretty great! Tooth of Eztli is also a Relic, so it can be grabbed and held by Dr. Elli Horowitz, who can hold up to 2 of them at once! This means Mandy has the very likely opportunity to have 2x Tooth of Eztli's in play at once (they are not unique), giving her +2 and +2 , and the possibility to draw 2 cards! HINT: ideal for The Forgotten Age.
Dr. Elli Horowitz: We all scratched are heads when Dr. Elli Horowitz was first announced--why the wording "Each relic"? Well, now we know why. The good doctor allows Mandy to hold up to 2 relics (Tooth of Eztli x2, since they are not unique, and later on, the Segment of Onyx without using up additional slots. Mostly you will find Elli holding your extra copy of Tooth of Eztli, bumping Mandy to a beefy 5 (or up to 7 with 2x loaded Hawk-Eye Folding Camera) and 5 , while also rewarding her by allowing her to draw 2 cards (!) when she inevitably passes her treachery tests. If you have Segment of Onyx in your deck, Dr. Elli Horowitz has the opportunity grab two at once! She can find any relic, so keep that in mind when upgrading. There are lots of good Seeker relics out there, like the Segment of Onyx, Segment of Onyx, Ancient Stone upgrades, Disc of Itzamna, Otherworldly Compass, Pnakotic Manuscripts, Otherworld Codex, Hemispheric Map, and the Key of Ys--many of which take up precious hand slots. Let me give you a hint: let Dr. Elli Horowitz hold them for you ;)
Mr. "Rook": The questionable dealer in secrets is Mandy's best friend and arguably one of the single best allies in the game--and Mandy literally makes him twice as good. She grants him the ability to search as deep as 12 cards; or search just 3, 6, or 9, and draw 2 (I'm personally fond of the search 6, draw 2). He is your best way to trigger the search-effect cards, like Astounding Revelation and Occult Evidence, and helps you pull out the exact card when you need to. The icing on the cake is that Rook's primary drawback doesn't even matter if you run across Shocking Discovery--it has no additional penalty! Rook is also ideal for sussing out Shocking Discovery early on as a way to weed it out of your deck. When he runs out of secrets, you can use Calling in Favors to pull him back to your hand, so you can replay him another day. Even if you don't (somehow) find another ally to play, you have a brand new Rook to deploy!
Research Librarian is in this deck for two reasons: (1) to grab the single copy of Occult Lexicon; and (2) as a way to purge Shocking Discovery. Ideally, you want to use his ability for #1. But here's an important warning: Research Librarian searches your ENTIRE deck, which means if Shocking Discovery is in it, the search will be canceled and no Occult Lexicon for you. He also works well with Calling in Favors. Use him wisely. Research Librarian often tends to get cut when upgrading later on. However, if you want to upgrade into cards like Otherworld Codex, Scroll of Secrets, or Pnakotic Manuscripts, you may want to keep him around, since he can fetch any of those as well!
Astounding Revelation: This is Mandy's true signature card. You can use it to recharge Mr. "Rook" or gain 2 resources. It's just good. With all the search effects in this deck, you should be triggering these regularly.
Calling in Favors: This is not just another search effect--it's an economy card, a way to recharge Mr. "Rook", and a way to find the actual ally you want to have in play. Calling in Favors has a lot of uses in this deck, including extending the soak potential of your allies. Did Dr. Elli Horowitz whiff on finding the relics you wanted? Call her favor in and take her back to hand. Is your precious Mr. "Rook" out of Secrets? Take him back into hand. Has your Research Librarian served his purpose, and not it's time for him to make room for an ally that's actually good? Call him in. At the very least, Calling in Favors is a way to double the secrets on Mr. "Rook". Once you pick up Charisma, you can search the top 9 cards of your deck and grab 2 allies, instead of 1, reducing the cost by BOTH!
Crack the Case: For Seekers, this is the more action-efficient version of Emergency Cache. Mandy is going to be clearing clues off locations, so you'll be able to get this to fire quite easily. Furthermore, Mandy can clear some pretty high-shroud locations, making the payoff potential higher than a plain ol' Emergency Cache. Not only is it Fast, you can distribute the resources gained among any investigators at your location! Mandy doesn't even have to be the investigator to clear the clues off! Do you want a really big payout? Use this to clear a location with the +3 Shroud from an Ancient Stone!
Deny Existence: This is an incredible card that gives Mandy the ability to resist huge damage hits like from Beyond the Veil, discarding a large hand of cards from a treachery effect, etc. At the very least it lets her tank a huge hit from a beefy enemy or boss for one round. Whatever the reason, this is a fantastic card to keep in your back pocket for a rainy day.
Mind over Matter: This is another rainy-day card you use for when things go south. It allows Mandy to split up from her fellow investigator, knowing that she can handle the odd enemy that comes her way. once you start upgrading, this card is usually a good candidate to cut.
No Stone Unturned: This card is not for you. Mandy can search her own deck just fine without wasting actions and resources on this card (though you could use this in a pinch--but that's not why it's in here). No Stone Unturned is for your fellow investigators, giving them the incredible ability to search for any card in their top 9 cards or any 2 cards in their top 6 (assuming you haven't been naughty and have already used up Mandy's special ability this round). Once you upgrade to the leveled No Stone Unturned, they will be able to search their entire deck for any 2 cards--WOW! This is one of the only team cards in this deck. Mandy's job is to investigate--it's everyone else's job to cover you!
Read the Signs: With 0 XP, Mandy doesn't have a lot of clue-acceleration. But this card is one of them. With some loaded Hawk-Eye Folding Cameras she will be able to take this test at anywhere from 8-10! You can laugh at Shroud values as your crush those tests AND grab 2 clues AND also ignore effects that happen when you investigate a location, such as those with the Haunted keyword. This is a nice investigate test to throw in a Deduction, just to kick the location while it's down.
Shortcut: There are few cards that are as unequivocally good as Shortcut. Keep this card in your back pocket until late in the scenario, when every action counts. At higher player counts, strongly consider upgrading this into Shortcut, which will create free actions for multiple investigators. Remember that you can Shortcut other investigators as well, which can be a very handy way to drag enemies around without incurring opportunity attacks.
Ward of Protection: Mandy is already good at resisting the encounter deck; Ward of Protection just makes her even better. Use this to cancel Ancient Evils, a treachery that will cause too much damage, or cancel drawing a treachery from the encounter deck due to a Shocking Discovery. Ward of Protection keeps Mandy protected and focused so she can grab all the clues.
Curiosity: With Mandy's card draw, she will often have a hand full of cards. This makes Curiosity a very versatile card to pull of high-shroud investigates (remember that Ancient Stone + Crack the Case combo I mentioned earlier?) or a way to bolster Read the Signs, or pass your common test.
Deduction: This is just an easy way to grab 2 clues instead of 1.
Eureka!: This is a card that mimics Mandy's ability. You can grab 1 card in the top 6, or 2 in the top 3. I find I usually do the latter. It is a fantastic way to filter out your random basic weakness if you know it's coming up, since you reshuffle after the test.
Inquiring Mind: Mandy is going to be at locations with clues, so it's easy to trigger these 3 icons. However, you may find that you eventually sub this card out as you upgrade.
Unexpected Courage: This is a -dense card that can be used for anything. It's all-around good.
Adjustments for 3-4 Players
There's honestly not a lot you can do for a 0 Experience Mandy deck to calibrate it for 3-4 players. This deck already has as much clue-acceleration she can get. However, if you are desperate for more clue-getting power, consider subbing in 2 copies of Drawn to the Flame in place of Mind over Matter and a copy of Calling in Favors.
If you want to try some different cards, check out these. Cards you can sub out of the given deck include Mind over Matter, No Stone Unturned (you can always pick up the upgraded version later), Calling in Favors, and possibly Curiosity.
REMEMBER: Mandy can only take up to 10 Events and/or Skills from her off-class. This deck only comes with 6 as-is. Keep that in mind when you're subbing in cards and for future upgrades!
NOTE: Mandy is particularly adept at solving all the seeker mini-quest cards (Strange Solution, Archaic Glyphs, Ancient Stone, Dream Diary). Often she can solve all of these in the first or second scenario! Her additional deck space also makes including these easier than ever. If you are going this route, also consider Shrewd Analysis, which can save you a lot of XP if you don't mind a little randomness.
Archaic Glyphs: essential if you plan on upgrading into the more powerful versions, especially if you want to upgrade into Archaic Glyphs for awesome clue-getting power. But be warned, it does occupy a hand slot, so you may need to replace your Fingerprint Kits to make room!
Ethereal Form: want a way to ignore enemies? Consider picking up Ethereal Form. Without any buffs, she tests at 6, which is really good. This is a great way to bait enemies and then ignore them, or a fantastic escape plan. Once she gets some powered-up Hawk-Eye Folding Camera's, she can test at 7 or even 8!
Delve Too Deep: this Mandy is not afraid of the encounter deck, and there is always something to spend XP on. Mandy's increased deck size also makes including cards like this easier. Seekers are increasingly hungry for XP, especially if they want to upgrade Archaic Glyphs, Strange Solution, and Ancient Stone.
Strange Solution: essential if you plan on getting the later upgraded versions. The best thing about the solutions is that they do not take up precious hand slots--or any slots whatsoever!
Dream-Enhancing Serum: this looks like a great Mandy card, but I have not personally had the pleasure of trying it.
Drawn to the Flame: this Mandy deck handles the encounter deck fairly well, so this can be an excellent way of grabbing 2 clues off a high shroud location.
"I've got a plan!": In two player, this might be a card to consider. It really helps your partner take out beefy enemies, especially bosses!
Grisly Totem: maybe you want more skill icons? This isn't a bad bet. It helps increase Mandy's efficiency. However, I personally find this less effective than the card draw afford by the Tooth of Eztli. I would suggest only going with one or the other--she only has one slot, unless you grab Relic Hunter.
There are not a lot of upgrades out there that Mandy really needs. With that said, I have listed some upgrades below in their order of relative value. As I mentioned earlier, Mandy is a great Seeker to solve all the in-game mini-quest cards, such as Archaic Glyphs, Strange Solution, etc.
Segment of Onyx x3: This is Mandy's second signature card. You should get all 3x copies as soon as possible, every time. Once you learn the power of the Pendant of the Queen, you will see why people want to build 30-card Mandy decks.
Deduction: This improves Mandy's clue-getting power without displacing any of your other cards. Always a solid (and for me, early) upgrade.
Archaic Glyphs: Watch Mandy grab ALL the clues with this.
Pathfinder: Do you remember how I told you Shortcut is so good? What about the same card on tap? Requiring no slots, Pathfinder creates incredible action compression for Mandy and you will never be sad to see it. At only 1 XP, it's also easy to acquire.
Ancient Stone: This opens up access to the upgraded stones, which Mandy can use quite, erm, handily.
Shortcut: At higher player counts, or in specific campaigns, consider upgrading into the leveled version of Shortcut. This lets other investigators use the ability once per round, which can be a crucial play in scenarios like The House Always Wins, and can cumulatively save a half-dozen or more actions among 3-4 investigators.
No Stone Unturned: Depending on your player count, this upgrade may be farther up the list. You don't really need the level 0 version of No Stone Unturned, but the leveled version allows any investigator to choose two cards out of their deck, using Mandy's special ability! Wow! Also, like the level 0 version, this card is not really for you. It's for your teammates--and what a card it is! Getting this in your open hand can be quite powerful. Since Mandy doesn't really need anything to start investigating, she will probably be fine with using this on her Guardian teammate so they can fetch their M1918 BAR + Contraband, or Flamethrower + Vicious Blow, etc. Going into a final battle? Use this card on your Mystic buddy so they can find their Shrivelling + Seal of the Elder Sign. Is the scenario really getting down the wire? Use this card on your Rogue teammate so they can grab a The Gold Pocket Watch and an Ace in the Hole. Really, the possibilities are endless, and this card allows investigator teams to grab the best possible cards for any situation.
Stargazing: This is a way to help your fellow investigators out. While in 2 player, you may not reap it's benefit as much, it still can provide some much-needed tempo. Mandy has the deck space for this.
Studious: This card gives Mandy lots of options. However, big caveat here: because you draw more cards in your opening hand and can mulligan more cards, you actually increase the likelihood of starting the game with Astounding Revelation and/or [Occult Evidence] (/card/06008) in your hand. On the flip side, it seems like a small price to pay.