Historical Rules · 23 April 2010
Rule 605.1a
Official source text from the 23 April 2010 Rules release
An activated ability without a target that could put mana into a player's mana pool when it resolves is a mana ability.
Historical Rules · 23 April 2010
Official source text from the 23 April 2010 Rules release
An activated ability without a target that could put mana into a player's mana pool when it resolves is a mana ability.