Raviel, Lord of Phantasms

Effect: This card cannot be Normal Summoned or Set. This card cannot be Special Summoned except by Tributing 3 Fiend-Type monsters on your side of the field. Each time your opponent Special Summons a monster(s), Special Summon a Phantasm Token (Fiend-Type/DARK/Level 1/ATK 1000/DEF 1000) on your side of the field. This Token cannot declare an attack. Once per turn, by Tributing 1 monster on your side of the field, increase the ATK of this card by the original ATK of the Tributed monster until the End Phase of that turn.