Manta Riders

{U}: This creature gains flying until end of turn.

Island

proxy

Mox Diamond

If this artifact would enter, you may discard a land card instead. If you do, put this artifact onto the battlefield. If you don't, put it into its owner's graveyard.
{T}: Add one mana of any color.

Blue Elemental Blast

Choose one —
• Counter target red spell.
• Destroy target red permanent.

Winter Orb

As long as this artifact is untapped, players can't untap more than one land during their untap steps.

Merfolk Looter

Rootwater Thief

{U}: This creature gains flying until end of turn.
Whenever this creature deals combat damage to a player, you may pay {2}. If you do, search that player's library for a card and exile it, then the player shuffles.

Survival of the Fittest

{G}, Discard a creature card: Search your library for a creature card, reveal that card, put it into your hand, then shuffle.

Getting

Yavimaya Coast

{T}: Add {C}.
{T}: Add {G} or {U}. This land deals 1 damage to you.

Reef Shaman

{T}: Target land becomes the basic land type of your choice until end of turn.

Squee, Goblin Nabob

At the beginning of your upkeep, you may return this card from your graveyard to your hand.

Hydroblast

Choose one —
• Counter target spell if it's red.
• Destroy target permanent if it's red.

Naturalize

Waterfront Bouncer

{U}, {T}, Discard a card: Return target creature to its owner's hand.

Forest

Lord of Atlantis

Other Merfolk get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)

Ceta Disciple

{R}, {T}: Target creature gets +2/+0 until end of turn.
{G}, {T}: Add one mana of any color.

Gilded Drake

Flying
When this creature enters, exchange control of this creature and up to one target creature an opponent controls. If you don't or can't make an exchange, sacrifice this creature. This ability still resolves if its target becomes illegal.

Counterspell

City of Brass

Whenever this land becomes tapped, it deals 1 damage to you.
{T}: Add one mana of any color.

Phyrexian Furnace

{T}: Exile the bottom card of target player's graveyard.
{1}, Sacrifice this artifact: Exile target card from a graveyard. Draw a card.

Mana Leak

Counter target spell unless its controller pays {3}.

Masticore

At the beginning of your upkeep, sacrifice this creature unless you discard a card.
{2}: This creature deals 1 damage to target creature.
{2}: Regenerate this creature.

Gaea's Skyfolk

Daze

You may return an Island you control to its owner's hand rather than pay this spell's mana cost.
Counter target spell unless its controller pays {1}.