MTG Land Calculator

This works out the land maths for a Magic: The Gathering deck from the hypergeometric distribution, which is the probability of drawing k lands in n cards without replacement. Give it the deck size, the land count and the opening hand size and it returns the full spread of lands in an opening hand, the chance of making every land drop through a chosen turn on the play or on the draw, and the smallest land count that reaches a probability you pick. London mulligan odds are exact, because putting the hand back and reshuffling makes each look an independent draw. It counts lands and nothing else, so cantrips, scry, mana rocks and fetch land thinning all sit outside it.