Historical Rules · 25 September 2014
Rule 202.1a
Official source text from the 25 September 2014 Rules release
The mana cost of an object represents what a player must spend from his or her mana pool to cast that card. Unless an object’s mana cost includes Phyrexian mana symbols (see rule 107.4f), paying that mana cost requires matching the color of any colored mana symbols as well as paying the generic mana indicated in the cost.