The Everforger 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

Rulebreaker — A deck with this commander can have artifact creature and Equipment cards of any color identity and any basic land cards. Whenever you cast an artifact creature or Equipment spell, you may copy that spell. Do this only once each turn. (The copy becomes a token.)