GRAVEKEEPER STRATEGY, PART 2 A Gravekeeper Deck is stronger if you play with "Necrovalley". It is a Field Spell Card that increases the ATK and DEF of every Gravekeeper monster by 500 points. Besides this amazing bonus, it also negates any card effect that affects a card(s) in the Graveyard, and prevents both players from removing cards in the Graveyard from play. - click here for another Dueling Tip.