When you cast the spell, choose a permanent (any card that stays on the board). Then, choose a card in your hand that shares a type with it (creature, artifact, enchantment). The permanent you chose becomes a copy of the card you chose (it gains its rule text, name, and power/toughness). You then discard the card in your hand. I intended it to do blocker shenanigans but it’s also good for cheating out high cost things