Offer 1 monster that includes "Gravekeeper's" in its card name on your side of the field as a tribute to inflict 700 points of Direct Damage to your opponent's Life Points. However, you cannot offer this card or another "Gravekeeper's Cannonholder" with this card's effect. Monsters used for a Tribute Summon or that are offered as Tributes due to other cards's effects are excluded.