Updated with nCr. You happy QuantumT?
Hm, what's your reasoning behind requiring exactly 3 pillars in the starting hand? I'd think that having more would be better. (True, drawing all pillars might be bad, but if that happens, chances are the next card'll be something else, which you can play).
Also, remember to account for automulligan + the fact that you have 12, not 10, quanta producing cards in your deck.
Edit: there's a .44515 chance of drawing 3+ pillars in the opening hand, by the way