When a Spell Card, Trap Card, or monster effect is activated, while both have "Gravekeeper's" monster and "Necrovalley" are on the field: Negate the activation, and if you do, destroy it. You can only activate 1 "Imperial Tombs of Necrovalley" per turn.
Near Mint Unlimited - $0.30
Lightly Played Unlimited - $0.20
Moderately Played Unlimited - $0.20
Heavily Played Unlimited - $0.20
Damaged Unlimited - $0.10