Since the checked box is immediately usable (unlike Delve Too Deep which let you shop for more only after clearing the scenario) you can :

• Make any Customizable with single box choice suddenly usable while playing the 1st scenario where you are not supposed to have any XP yet.
• When you are missing only 1 box to get a key upgrade from all the XP you got in your previous scenario, or you may intentionally check boxes such that it is missing just 1 and use remaining XP for regular card purchases instead. Carrying Refine into the next scenario and bet for it to check the final box can stretch the limit of how fast you can get good in first half of the campaign.
• Maybe able to stretch this more with In the Thick of It, for example checking 3/4 box of Pocket Multi Tool Spring-Loaded then bet on Refine to check the final box. Or starting Runic Axe with Saga and then use Refine to add one more inscription inside the scenario to go with it.

Also, if you are planning to add in some Customizable cards into the deck later together with boxes checked (e.g. would rather use deck space for something else than 2x Summoned Servitor in the 1st scenario that cannot do anything), then you do not "own" the card just yet, and cannot use Refine to check the box. (However 1x Summoned Servitor is enough to receive Refine.)

(Ownership and Control : A card's owner is the player whose deck (or game area) held the card at the start of the game.)

This is a fantastic card if you are using custom cards.

While it seems extremely taxing at 3r, a card, and being a double for a mere 1 XP, its important to remember that the main way you get XP in this game is clearing victory locations or enemies, and mostly locations. In that context, is that a bad price?

No, not at all, its fantastic. Because this gives 1 XP for the player using it, and costs only the player using it actions and resources, you can compare it to how much it would cost you to get an extra victory point in a true solo game: You need to move into and out of a location that is otherwise superfluous, and need to pass 2-3 investigation tests or discover 2-3 clues, often times facing some sort of negative location effect. That is, in almost all cases, going to cost you MUCH more than 2 actions, a card, and 3 resources. Specific seekers might be able to get a VP for less with double pathfinder, assuming on their turn they didn't want to move anyway and were just 'popping in' to a location, investigating twice, and popping out, but in practice you probably are still spending time and energy in 99% of decks.

So when you look at it that way, its a fantastic investment of actions to VP, in multiplayer or solo, regardless of how many people run it, because it scales more aggressively for you than VP locations. You just play it during a turn your partially moving to a new location or any other 'administrative' turn where the team needs to just shuffle about and now your deck is stronger, which makes future scenarios easier, which gives you more time to get XP, which makes playing this card easier.

The other obvious benefit is that the XP comes from the aether, which matters if you are doing well and playing strong decks that tend to clear VP most or all of the VP of a scenario with some time to spare. At some point you can't get anymore XP from a scenario no matter how well you do, and Refine increases that max XP by 1, at least for you.

Also of important note is that you definitely should focus on VP locations over this card if your the cluever, because those pay out to the team. But it is very rare for you to literally not have 2 spare actions in the game as a cluever to cram in at some point. If you have custom cards and spare deck slots, definitely run this card for at least the first few scenarios.

I still can’t really figure out if this card is good or not. Scarlet Keys is extremely stingy with XP so far — I’ve played three scenarios and gotten a total of 5 XP. Yet, I’ve also taken Down the Rabbit Hole and so my customizable cards already have a total of 7 checkboxes checked, which is nice. Still, two actions and three resources is expensive, and it feels really bad to tell my teammates, “Hey, I’m gonna move once this turn and then give myself an XP.”

hey just noticed you can put this under Stick to the Plan. Nice to be able to reduce to one of these in a deck if you're going Carson (or whomever) upgrade path on Customizable cards. 200 characters here I come.

This card is not so fit for cluever in my opinion. According to my practical run they barely have free time for some DIY hobby.

I just finished EotE. I went greedy and got 2 copies of Refine on most of the scenarios. And manage to only land 2 Refine played throughout unskip EotE. Moreover, I felt some small sense of guilt each time I played it. Some of investigator-mate even upgrade leaning a bit toward clue getting afterward.

I should notice the fact earlier but sometime you just learn from a card. Cluever is generally busier. If you are fighter probably got some peaceful time when enemy not spawn.

Does Refine let you check the Inscription of the Hunt box on Runic Axe now that it's chained? If so, does that cost you XP mid-scenario? I was planning to play both in my deck anyway, and when I went to look it up I couldn't find any information about it.