While it may be old news to most, I just had to point it out that in Turbo pack 2, they have reprinted Necrovalley. To my great surprise and delight, it had gone through an errata.
TU02 Necrovalley
Negate the effects of Spells, Traps and Effect Monsters that target a card(s) in either player's Graveyard. Cards in either player's Graveyard cannot be removed from play. All "Gravekeeper's" monsters gain 500 ATK and DEF.
Until now, Necrovalley has stated that it negates effects that involve or affect cards in the grave. I have used this card for years and people have never really understood what the card actually did because of these confusing key words. This has been fixed now, so lets all do a dance now that it says what it truly does.