You can have only 1 face-up Gravekeeper''s Chief on your side of the field at any time. As long as this card remains face-up on the field, your Graveyard is not affected by Necrovalley. When you Tribute Summon this monster, you can Special Summon 1 monster that includes Gravekeeper''s in its card name from your Graveyard.
Near Mint Unlimited - $1.00
Lightly Played Unlimited - $0.85
Moderately Played Unlimited - $0.70
Heavily Played Unlimited - $0.60
Damaged Unlimited - $0.50