Book of Eclipse — Ruling

Effetto 0

This card can only be activated if there is at least one face-up non-Link Monster in a Monster Zone.
When resolving the effect during the End Phase, if your opponent is unable to draw cards due to a card effect, flip all face-down Defense Position monsters on their field to face-up Defense Position, and the effect's resolution will end there.
This card can be activated even if the opponent currently cannot draw cards, such as due to a card effect, or because there are no cards in their Deck.
When resolving the effect during the End Phase, if the number of cards in your opponent's Deck is lower than the number of face-down Defense Position monsters on their field, you first flip all of those monsters face-up, and then your opponent loses the Duel due to being unable to draw the required number of cards.
When the effect resolves during the End Phase, you first change your opponent's face-down Defense Position monsters to face-up Defense Position. Afterwards, they draw a number of cards equal to the number of monsters flipped face-up this way. (These are not treated as having happened simultaneously.) No Chain Links are formed when applying this effect during the End Phase.
This card cannot be activated during the Damage Step.