Counterspell

Tidal Warrior

{T}: Target land becomes an Island until end of turn.

Island

Merfolk Mistbinder

Lórien Revealed

Draw three cards.
Islandcycling {1} ({1}, Discard this card: Search your library for an Island card, reveal it, put it into your hand, then shuffle.)

Mox Sapphire

Censor

Counter target spell unless its controller pays {1}.
Cycling {U} ({U}, Discard this card: Draw a card.)

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Mox Emerald

Tropical Island

Blue Elemental Blast

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

Triton Shorestalker

Vodalian Mage

{U}, {T}: Counter target spell unless its controller pays {1}.

Lord of Atlantis

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

Forest

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Gitaxian Probe

({U/P} can be paid with either {U} or 2 life.)
Look at target player's hand.
Draw a card.

Dismember

({B/P} can be paid with either {B} or 2 life.)
Target creature gets -5/-5 until end of turn.

Black Lotus

{T}, Sacrifice this artifact: Add three mana of any one color.

Wear Away

Destroy target artifact or enchantment.
Splice onto Arcane {3}{G} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)