Artillery Enthusiast 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

Modified creatures you control have menace. (Equipment, Auras you control, and counters are modifications.) When Artillery Enthusiast enters, you may discard a card. If you do, seek a card with mana value equal to that card's mana value. (To seek a card, put one at random from your library into your hand.)