11 books?

[teelaurila]

So I got 11th book from treasure...?

edit: spell costs seem to have gone down another 6%

[Seravy]

Yes, you can get it and yes, it reduces costs and increases research speed, but does nothing else.

[teelaurila]

... and now it's 12 books. For another 5%. 

Looks like I am casting at 72% of cost. Summons at 56%
Multiplying the reductions: 12%, 10%, 5% and 5% become 71.4% and another 25% for summons becomes 54%.
For some reason the math is close but not quite.

[teelaurila]

...ummm ... 13! (I wonder what's the record/limit)