Castle Vantress

Castle Vantress enters the battlefield tapped unless you control an Island.
{T}: Add {U}.
{2}{U}{U}, {T}: Scry 2.

Thassa, Deep-Dwelling

Indestructible
As long as your devotion to blue is less than five, Thassa isn't a creature.
At the beginning of your end step, exile up to one other target creature you control, then return that card to the battlefield under your control.
{3}{U}: Tap another target creature.

Island

Omen of the Sea

Flash
When Omen of the Sea enters the battlefield, scry 2, then draw a card.
{2}{U}, Sacrifice Omen of the Sea: Scry 2.

Solemn Simulacrum

When Solemn Simulacrum enters the battlefield, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When Solemn Simulacrum dies, you may draw a card.

Counterspell

Scourge of Fleets

When Scourge of Fleets enters the battlefield, return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control.

Sol Ring

Ravenform

Exile target artifact or creature. Its controller creates a 1/1 blue Bird creature token with flying.
Foretell {U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Vedalken Orrery

You may cast spells as though they had flash.

Curse of the Swine

Exile X target creatures. For each creature exiled this way, its controller creates a 2/2 green Boar creature token.

Spell Snuff

Counter target spell.
Fateful hour — If you have 5 or less life, draw a card.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

The Surgical Bay

The Surgical Bay enters the battlefield tapped.
{T}: Add {U}.
{1}{U}, {T}, Sacrifice The Surgical Bay: Draw a card.