Reaper Leviathan, Death Snake

Haste, Vigilance, Deathtouch, First strike, Flash
When Reaper Leviathan, Death Snake enters the battlefield, all under water cards take 6 damage and are unable to untap on the untap phase.
When Reaper Leviathan, Death Snake attacks scry 3, then exile 1 of the top 3 cards.
-{3}, {u/b}{u/b}, Tap Target creature you dont control and do its damage to its toughness.
-{5}, {u/b}{u/b}{u/b}, Reaper Leviathan, Death Snake gains unblockable or double strike until end of turn