The Snapstone Wielder is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

If The Snapstone Wielder is your commander and your deck contains no land cards, your starting hand size is four and for the rest of the game, at the beginning of your upkeep, you get a mana counter. During each of your turns, you can spend mana of any color equal to the number of mana counters you have. (You want mana on opponent's turns, you're on your own. Who needs instant-speed interaction?) Whenever The Snapstone Wielder enters or attacks, cast a random nonland Magic card without paying its mana cost. If it has targets, choose the targets at random.