Historical Rules · 13 November 2015
Rule 305.2a
Official source text from the 13 November 2015 Rules release
To determine whether a player can play a land, compare the number of lands the player can play this turn with the number of lands he or she has already played this turn (including lands played as special actions and lands played during the resolution of spells and abilities). If the number of lands the player can play is greater, the play is legal.