Gravekeeper's Oracle (MP14-EN215) [2014 Mega-Tins Mega Pack]

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 the 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 and DEF.