An enormously strong card that encourages Seekers to build around it in multiplayer games. By itself, it will probably only net you one, maybe two extra clues at best, and that is assuming the chaos bag doesn't entirely hose you.

Enter Higher Education.

Every resources invested in Higher Education while using Guiding Stones essentially picks you up an extra clue (assuming you don't auto-fail) which is immensely strong in multiplayer. Rex especially, who has access to Burglary, can generate up to 4 resources and 1 clue with a single action (Burglary + Dr. Milan Christopher) and then follow it up by picking up 4 to 8 clues with Guiding Stones depending on shroud and chaos token drawn. Other Seekers can't generate resources quite as quickly as Rex can, but anyone with access to Dr. Milan should be able to have powerful turns with Guiding Stones.

Minh Thi Phan is runner up for using Guiding Stones well, as she gains +4 Intellect from Inquiring Mind and potentially +5 from Desperate Search. Playing at 3 or less Sanity is pretty dangerous, but a little more manageable for Seekers now that they have access to Logical Reasoning. And a Minh deck filled with skill cards will probably have more free resources to spend on Higher Education than a Daisy deck will.

Just don't bother playing it in solo games, as locations simply won't have enough clues at them to take advantage of the power of Guiding Stones.

I think The Skeleton Key should definately part of the conversation. I played a duo game with Daisy Walker and Preston Fairmont. Preston moved the key around & Diasy and stripped the clues from every location with Deduction, this card, and Perception.

Guiding Stones is an incredibly powerful card in Rex Murphy and Monterey Jack, especially with a full 4 player group. They both can start with Well Connected, then run a resource heavy build. When you're sitting on 40 resources, you're suddenly vacuuming up 6+ clues in an action. Incorporate Alchemical Distillation with an Enlightened Distillate, suddenly you've got a near endless supply of location emptying charges.

I could see a strong build with Eldritch Sophist and investigators with Mystic splash too. Daisy for sure. Or even Ursula, since many relics come with charges that Sophist can move. Looking at the self-replenishing Runic Axe. Gimmicky, but fun!

Keep in mind, this card is most effective in multiplayer, and most often only CRAZY on high-clue low-shroud locations. It's an almost niche specialization, best when there are mountains of clues to tackle.

This is a very good card in multiplayer, 3 times. Or 2 if you pull the tentacle.

What characters can use this well (can buff intellect) and also can recharge this card?

Ursula can regain one charge with eldrich sophist and red clock, but that's expensive in xp and you can only have one clock in your entire deck (also hope you have both other cards available). She can also take Skeleton Key if you've got high shroud locations.

Akachi struggles to get enough intellect to use it well, but can easily recharge it with mystic cards, and starts with one extra charge.

Daisy has a tome that can add one charge per turn (one action for one charge isn't usually good, but she can ignore the action cost once per turn), but is usually too busy using tomes to investigate, and has already spent her resources.