Leviathan [The Dark] Shadows over Innistrad Prerelease Promos Set: Modern Masters 2017 Type:

Set: Modern Masters 2017 Type: Creature — Human Wizard Mythic Cost: {1}{U} Flash When Snapcaster Mage enters the battlefield

And at his passing

Set: From the Vault: Lore Type: Instant Mythic Cost: {1}{B} Add {B}{B}{B}

that player skips that turn instead

Leviathan [The Dark] Shadows over Innistrad Prerelease Promos Set: Modern Masters 2017 Type:Set: The Dark Type: Creature Leviathan Rare Cost: {5}{U}{U}{U}{U} Trample Leviathan enters the battlefield tapped and doesn't untap during your untap step. At the beginning of your upkeep, you may sacrifice two Islands. If you do, untap Leviathan. Leviathan can't attack unless you sacrifice two Islands. (This cost is paid as attackers are declared.)