
I think this card is a bomb. I think this immediately becomes one of the highest-priority Seeker XP cards. You'll still want to pick up Higher Education first, of course (which will conveniently help with identifying the Ancient Stone.) But I wouldn't wait too much longer to get this going. This card is going to make you win much more reliably.
Test-free damage is golden in this game. There's a reason why Agnes Baker is almost always ranked as a high-tier investigator, why Zoey's Cross is one of the best special investigator cards, and why Beat Cop II is one of the best uses of 2 XP. The primary source of challenge in this game comes from enemies, and being able to kill them or finish them off without any skill tests makes the game way, way easier.
So I expect this card to be superb. In addition to being test-free, the damage is quite efficient! Depending on circumstances, you may not have to spend an action at all. If you do have to spend an action to get a needed point of damage, you get a draw out of it.
Obviously, you can combine this with Cryptic Research, Search for the Truth, Analytical Mind, and the like, all of which are just absurdly powerful plays. But don't forget the simpler skill cards like Perception, Overpower, Eureka!, etc.
The synergy for Daisy with Old Book of Lore is going to be incredible, too, although the hand slot consideration makes this tricky for her. Still, that's going to be extremely powerful when it works.
I think the number of secrets you need to make this a good card is actually quite low. Even at four secrets, I think this card would absolutely be worth it. You should be able to get a lot more than that--I see no reason why you shouldn't get seven secrets on this thing--which makes this just amazing, in my opinion.
Finally, remember that reaction triggers are optional. So if you find yourself in a situation where you're drawing a card but the point of damage won't make a difference, you don't have to waste a secret.