The Darkhold 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

: Put a sin counter on The Darkhold. Draw a card for each sin counter on it, then you lose 1 life for each card in your hand. , : Each player's life total becomes the lowest life total among all players. Activate only as a sorcery.