Stonecoil Serpent

Reach, trample, protection from multicolored
Stonecoil Serpent enters with X +1/+1 counters on it.

Denizen of the Deep

When Denizen of the Deep enters, return each other creature you control to its owner's hand.

Slipstream Serpent

Slipstream Serpent can't attack unless defending player controls an Island.
When you control no Islands, sacrifice Slipstream Serpent.
Morph {5}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Sea Monster

Sea Monster can't attack unless defending player controls an Island.

Island

Frilled Sea Serpent

{5}{U}{U}: Frilled Sea Serpent can't be blocked this turn.

Serpentine Ambush

Until end of turn, target creature becomes a blue Serpent with base power and toughness 5/5.

Striped Riverwinder

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Cycling {U} ({U}, Discard this card: Draw a card.)

River Serpent

River Serpent can't attack unless there are five or more cards in your graveyard.
Cycling {U} ({U}, Discard this card: Draw a card.)

Tolarian Terror

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)

Scrapdiver Serpent

Scrapdiver Serpent can't be blocked as long as defending player controls an artifact.

Deep-Sea Terror

Deep-Sea Terror can't attack unless there are seven or more cards in your graveyard.

Gearseeker Serpent

This spell costs {1} less to cast for each artifact you control.
{5}{U}: Gearseeker Serpent can't be blocked this turn.

Cryptic Serpent

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.

Spire Serpent

Defender
Metalcraft — As long as you control three or more artifacts, Spire Serpent gets +2/+2 and can attack as though it didn't have defender.

Dirgur Nemesis

Defender
Megamorph {6}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)

Shoal Serpent

Defender
Landfall — Whenever a land you control enters, Shoal Serpent loses defender until end of turn.

Steelclad Serpent

Steelclad Serpent can't attack unless you control another artifact.

Harbor Serpent

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Harbor Serpent can't attack unless there are five or more Islands on the battlefield.

Wormhole Serpent

{3}{U}: Target creature can't be blocked this turn.

Serpent of the Endless Sea

Serpent of the Endless Sea's power and toughness are each equal to the number of Islands you control.
Serpent of the Endless Sea can't attack unless defending player controls an Island.