What’s the best book you’ve found for genuinely improving probabilistic thinking?

One thing I’ve noticed after doing a lot of quant prep is that there’s a huge difference between books that teach tricks and books that genuinely improve the way you think. For me, Quantitative Finance Interview Prep Guide by Mikhail Zaitsev (who’s a Jane Street quant) was one of the rare books in the second category. The problems are hard in a very “clean” way, they force you to build intuition for probability and combinatorics instead of pattern-matching formulas. Ironically, despite the title