Blood Mefist [YCSW-EN004] Ultra Rare Return of the Duelist then target 1 Set card

then target 1 Set card your opponent controls

If this face-up card would leave the field

except "The Grand Spellbook Tower"

this card gains ATK equal to the Tributed monster's ATK

Blood Mefist [YCSW-EN004] Ultra Rare Return of the Duelist then target 1 Set cardSet: Yu Gi Oh! Championship Series Prize Cards Card type: Synchro Effect Monster Rarity: Ultra Rare Attack: 2800 Defense: 1300 1 Tuner + 1 or more non Tuner monsters Once per turn, during your opponent's Standby Phase: You can inflict 300 damage to your opponent for each card your opponent controls. Each time your opponent Sets a Spell or Trap Card(s): Inflict 300 damage to your opponent.