If only your opponent controls a monster, you can Special Summon this card (from your hand).
Raviel, Lord of Phantasms
ATK 4000DEF 4000
Cannot be Normal Summoned/Set. Must be Special Summoned (from your hand) by Tributing 3 Fiend-Type monsters, and cannot be Special Summoned by other ways. If your opponent Normal Summons a monster(s): Special Summon 1 "Phantasm Token" (Fiend-Type/DARK/Level 1/ATK 1000/DEF 1000) for each monster Summoned, but it cannot declare an attack. Once per turn: You can Tribute 1 monster; this card gains ATK equal to the original ATK of the Tributed monster until the end of this turn.