Its a feature that lets you give one 1-4-diamond rarity card to your in-game friendsand receive one in return
They don't copy whether that creature is tapped or untapped, whether it has any counters on it or Auras and Equipment attached to it, or any non-copy effects that have changed its power, toughness, types, color, and so on
For example, creating three Rhystic Study copies makes it almost impossible for your opponents to play the game without feeding you cards, multiple Archangel of Tithes shuts down attackers, and so on
In a regular Limited environment, focusing your picks around a gold card is exactly what you shouldnt do
Psionic Ritual lets you free-cast an instant or sorcery spell from your graveyard, and replicates by tapping horrors
Edgar Markov puts an incredible amount of pressure on the board early, and playing some amazing MTG cards with low-mana costs from your hand will help you flood the board before turn four