I notice that a lot of the discussion I see about this is in regards to actually gaining XP from Down the Rabbit Hole (DtRH), but I think it has more to offer than that.

DtRH offers more than just some savings on XP, and I think the important thing to realize here is that you don't need to have a net positive XP gain, or even net 0. I'm of the opinion that this card is amazingly good even when it costs you XP. That might seem counter intuitive, but I prefer to look at this as acceleration for your deck's power at the start of the campaign. If it saves you XP on (for example) the first three scenarios, and you don't go negative until scenario 5 or 6, that means you're above the XP curve on 5 of the 8 scenarios, and only below for the last 2 or 3.

I think this is an amazing advantage of DtRH, since Arkham is a game where a lot of the difficulty is in the early scenarios, before your deck has all of the cards that it needs, and thus where you have more limited options. Additionally, early game XP means you're better equipped to take all the XP from those early scenarios, which means you indirectly get even more XP from DtRH. This means you can snowball into the late game with XP for your entire party, and with several good scenario resolutions under your belt.

This is opposed to the late game, where you probably already have a solid deck, and so can afford to take a penalty on the cards you purchase because you're going to feel that a lot less. Another way to look at this is that getting +1 or +2 XP when you only have ~10-20 XP is a %10 increase, where as in the late game where you can have 60+ XP, the penalty of +1 XP per card is just a lower percent of that.

In the end, I see this card as not being too dissimilar to early promoting in Fire Emblem. You're trading your potential late game power for an early game advantage. I think in Arkham (as in the Fire Emblem games I've played) that's a trade that will work out better for you in the long run.

This card is a cool replacement for Arcane Research, or a nice boost to it, depending on your upgrade line. HOWEVER, It is an anti-fun card.

This card essentially makes it so you build a deck with a bunch of purchasable upgrades, and reduces your desire to get new cards. Now you could see it as offsetting the new cards, by only buying 1 new card a scenario, and upgrading atleast 1 card, leading to a net 1xp gain. For "every mystic deck ever" archetypes this card is strong.

However, If you enjoy breaking the mystic mould I see this as a detriment. This card keeps you on the straight and narrow, upgrade your Shrivelling, Rite of Seeking, Mists of R'lyeh. Grabs you Recharge, Arcane Initiate, and Ward of Protection, Grotesque Statue, Robes of Endless Nightand have at it. I just see this as dull. Don't get me wrong those cards are all core because of how powerful they are and I would take them and this upgrade into a difficulty spike campaign i.e. trying to beat expert or complete achievements, but for standard this is a buzzkill.

Is this card good or bad? as a mystic running your typical build this card is insane, as someone who loves pure xp it's insane value, but as someone who enjoys trying new builds and playing with non typical cards this isn't the card for you.

This card is about to increase in value with the reveal of the Customizable keyword in the Scarlet Keys cycle. The details of this keyword were recently revealed (https://twitter.com/NatsunoYoru/status/1545188668570214400) on Twitter by MJ Newman.

Now, simply including a card like Hunter's Armor will provide you with seven different upgrade options - each one easily discounted by 1XP with Down the Rabbit Hole. And that's only one of the customizable cards we've seen so far! Customizable cards will also scale better than many other cards in the game, lowering the requirement for you to purchase new cards in the first place.

I wonder, how this card interacts with (non-level 0) Myriad cards. Initially I thought, they should cost +3 XP, if you take a set of three. But the rule for Myriad states: Additionally, when you purchase a myriad card for your deck, you may purchase up to two additional copies of that card (at the same level) at no experience cost. Because "no" is not a numeric like "0", you could add to, I do now think, that you can replace cards into them just for +1 XP.

I want to love this card. It feeds my munchkin brain in a good way!

In theory, even if you buy cards that are new for your deck, it will still be worth it if your original decklist features enough upgradeable cards.

For every 2 upgraded cards, a new card can be added while maintaining advantage. If you want to have the highest experience advantage, you need 14 upgrade cards in a regular 8 game campaign. If you merely want to stay neutral or above, then you'd be able to add 13 card in the same scenario. That would make you gain 14 upgrade exp with a 13 exp penalty for adding new cards (which would still be net-positive).

This card rewards pre-emptive planning and deckbuilding and gives more experience very early on.

How does this card interact with buying new Lvl 0 cards? I'm playing a campaign RN and it's not exactly clear so I can't be trusted to be impartial about it.

From Campaign Play in the rules reference: Each card costs experience equal to the card's level, to a minimum of 1 (purchasing a level zero card still costs 1 experience). The number of pips beneath a card's cost indicates the card's level.

Additionally, from 1.8 "Game Play" in the FAQ: When purchasing a new card during campaign play, an investigator must pay a minimum of 1 experience. As a result, level 0 cards cost 1 experience to purchase. This minimum only applies when purchasing new cards. It does not permanently alter a card’s level or experience cost, and does not apply when upgrading a card to a higher level version.

The way that I read it, as specified by the FAQ, Lvl 0 cards cost 0 XP, but because the cost of adding a new card to your deck must be at least 1, the cost is brought up to 1. My question is this -- does the increased price from DtRH apply to the 0-XP cost of adding a Lvl 0 card before the 1-cost minimum is checked, and if so, does having the price increased from 0 to 1 satisfy the 1-cost minimum? All told, does adding a new Lvl 0 card to your deck with DtRH cost 1 XP or 2?

I can't help but notice that Edge of the Earth comes with a lot of level 1+ cards that can be upgraded further. This includes a whole Spell suite, like Divination (1) and Divination (4), which are also good with Arcane Research, but then also stuff like On the Trail (1) and On the Trail (3) and Ice Pick (1) and Ice Pick (3), among others. This synergizes with the investigators in this set that have very limited access to their "off-class" level 0 cards, but also seems like an interesting puzzle with Down the Rabbit Hole. Lily Chen can take this card and use it to discount the upgrade from Butterfly Swords (2) to Butterfly Swords (5), and Norman Withers can do the same for Blur (1) to Blur (4), although it will take one of his 5 Mystic Level 0 slots.

But considering the drawback of this card, is it worth it? You'll pay an extra XP just to get the new Level 1 card in your deck, and get refunded that penalty when you upgrade. Net XP, zero. Ideally, you need to have 14 cards to upgrade in a 8-scenario campaign to get the full value here (we'll see how Edge of the Earth's supposedly different campaign structure affects this), so you'd better really want those non-Level 0 upgradable cards. The EOTE investigators don't really have any other options, though, because Lily & Norman don't have that many Level 0 cards that they could take that upgrade into cards of their "off" class. So, frankly, this card anti-synergizes with the investigators in the box. Your only out is to take In the Thick of It and some trauma for three Level 1 cards, but there still aren't going to be enough cards to upgrade. Strange. But it makes me think we'll have future cards that give you an XP bonus for upgrading cards, without this particular drawback, or more ways to start your deck with non-level 0 cards.

Other Mystics & off-class Mystics should consider this card, though, because of the variety of upgrades now available, including in this set. Daisy Walker can get a discount on upgrading Professor William Webb, and take In the Thick of It to get the upgrade for Eon Chart, among other things. And Father Mateo, starting with an extra 5 XP can spread it out across five Level 1 Spells and get a further discount with an Arcane Research or two, or maybe just spend your starting XP on cards you can't upgrade and don't want the penalty on, and use your Down the Rabbit Hole to upgrade Guts and Robes of Endless Night. Up to you!

Exile states "If exiling 1 or more cards would reduce your deck below your investigator's deck size, when purchasing cards between scenarios, you must purchase cards so that a legal deck size is maintained (when purchasing cards in this manner, you may purchase level 0 cards for 0 experience cost until a legal deck size is reached)."

But purchasing cards for 0 xp is still purchasing a new card, and thus has its cost increased to 1, right? So what if you have fewer xp than missing cards in your deck?