Number C39: Utopia Ray Victory (UTR) [JOTL-EN048] Ultimate Rare Synchro/Effect Monster Leviathan can't attack unless you

Leviathan can't attack unless you sacrifice two Islands

or another monster's effect

You can only use this effect of "Ghost Belle & Haunted Mansion" once per turn

Her diligence in pursuing both is her greatest asset

Number C39: Utopia Ray Victory (UTR) [JOTL-EN048] Ultimate Rare Synchro/Effect Monster Leviathan can't attack unless youSet: Judgment of the Light Card type: Xyz Effect Monster Rarity: Ultimate Rare Attack: 2800 Defense: 2500 3 level 5 monsters If this card attacks, your opponent cannot activate any Spell Trap Cards until the end of the Damage Step. If this card has a "Utopia" monster as an Xyz Material, it gains this effect. When this card declares an attack on a face up monster your opponent controls: You can detach 1 Xyz Material from this card; negate that