Gravekeeper's Oracle (SBC2-ENF13) [Speed Duel: Battle City Finals]

You can Tribute 3 monsters or 1 "Gravekeeper's" monster to Tribute Summon (but not Set) this card. When this card is Tribute Summoned: You can activate any of these effects, and resolve in sequence, up to the number of "Gravekeeper's" monsters Tributed for its Summon;<br>• This card gains ATK equal to the combined Levels that all monsters Tributed for its Tribute Summon had on the field x 100.<br>• Destroy all Set monsters your opponent controls.<br>• All monsters your opponent currently controls lose 2000 ATK/DEF.