Disclaimer: I have not yet played this card.

Let's analyse it from a purely mathematical perspective: It costs 2 resources, a card and an action to put to play. It comes in with 0 resources. Meaning you have to discover clues 2 separate times (since it gives you a resource for each time you discover clues, not each clue discovered) in two separate turns (it exhausts) to break even just for the resource cost. If we assume the usual "an action is roughly equal to a card which is roughly equal to a resource", you only break even after 4 turns of investigating.

Actually, not even that, since it only pays for Spells cards.

To paraphrase an artist: "there are builds, I'm sure", if you already have Geared Up in mind it saves you a resource and (potentially) an action. But it's kinda hard to see a deck that would need Spell economy whilst having so many Items to justify Geared Up.

I understand the designers were terrified of another Dr. Milan Christopher, but this seems far too niche to be useful for anybody. Maybe if it cost 0. Maaaaaybe if it was fast. Maybe if it used charges instead of resources.

Making this card belong to Seekers is a baffling decision: there just aren't that many spell cards in their class, and some of them cost 0 already (https://arkhamdb.com/find?q=k%3Aspell+f%3Aseeker&decks=player)

I get Agatha is a Seeker but she is also a Mystic. so I don't see the reason why to gate this card to be Seeker-only: it should be Mystic or double class

This already suffers from the issue of other economy cards (if you draw it early, great! If you draw it later in the level, it's useless), and it's only useful if you are planning to Investigate/discover clues, but printing it as a Seeker-only card kill all of its utility.

Right now the only people I can see this being even remotely okay on are Seekers with Mystic access, like Daisy, or Mystics with Seeker access, like Marie and Luke

Like a lot of cards from this set, it feels very underpowered, and not even in a way that can inspire creativity to make it work. The main character I can think that would want to use this is Mystic Agatha (Seeker Agatha presumably would not be using enough spell events to justify this card and also has the seeker pool for more cracked income generation), and Mystic Agatha can easily get by the entire scenario with Voice of Ra cast twice (once normally, once in discard). Resources are most valuable early on in the scenario when you need to get setup and get some momentum. This card maybe promises to generate enough income as a completely wiffed Voice of Ra/get a resource basic action after three turns. Weird.

I am going to attempt to put a positive spin on this card by trying to identify its most apparent niche.

Spell events are great. I love spell events. They are typically really impactful, but they're also really expensive. So lets say Luke Robinson wants to run Dayana Esperence with Read the Signs, but that's some pricy tech, you gotta muster up 2 resources every time you wanna do that. But by spending 4 resources and 2 actions, you can make this combo pay for itself. That's something, sort of.

And you can apply Fine Tuning to these cards, so you can trigger them twice per turn. That means that for 8 resources and 2 actions you can generate 4 resources per turn dedicated to playing spells. Not the worst engine, and it only costs 2 XP and 4 card slots. Getting the startup money is hard but not insurmountable, and if you're gonna be playing a lot of spells and getting a lot of clues then it will pay off.

Consider Prophetic. For 3 XP and 3 Resources you can get 2 resources per turn that can be spent on Spells, Fortune, and Spirit Cards, and can alternatively be spent on boosting tests on those same cards. Two copies of Mortar and Pestle is 1 more resource and 1 more action to play and requires you get clues to acquire those resources. Is Prophetic Clearly better? Yes, absolutely, but it also costs 3 XP and is restricted to Level 3 Guardian/Mystic/Survivor access. Mortar and Pestle can be taken by anyone with level 0 Seeker access, has synergies with other Seeker cards, and can bank its resources for later turns, something you can't do with Prophetic.

Is this an auto-take for 99% of builds? Absolutely not. But it's a card that I think you can extract a lot more value from than it first seems, especially if you're running Dayana Esperence and can reliably get clues.