The Fearsome Flock 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

Flying, split second level up (: Put a level counter on this. Level up only as a sorcery. This can't be responded to.) LEVEL 1-3 3/3 Flying Whenever The Fearsome Flock deals combat damage to a player, gain control of target noncreature artifact that player controls. It becomes a Treasure. LEVEL 4+ 3/4 Flying You may activate abilities of artifacts your opponents control as though you control them.