Arzakon 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

+2: Arzakon deals 3 damage to any other target. −3: Create a Black Lotus token. (It's a artifact with ", Sacrifice this token: Add three mana of any one color.") −7: Each player shuffles their hand and graveyard into their library, then draws seven cards. Arzakon can be your commander.