Bone Mask — ruling 1

If you do not have enough cards in your library, the damage is still prevented and all the cards in your library are exiled.

Bone Mask : règles, fonctionnement et interactions (MTG)

Bone Mask 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

, : The next time a source of your choice would deal damage to you this turn, prevent that damage. Exile cards from the top of your library equal to the damage prevented this way.

How it works : Bone Mask

Original English text — Wizards of the Coast / Scryfall

#1October 4, 2004· Wizards of the Coast
If you do not have enough cards in your library, the damage is still prevented and all the cards in your library are exiled.
No other card is named in this ruling.