Force of Will

You may pay 1 life and remove a blue card in your hand from the game instead of paying Force of Will's casting cost. Effects that prevent or redirect damage cannot be used to counter this loss of life. Counter target spell.

Cavern of Souls

As Cavern of Souls enters the battlefield, choose a creature type. {T}: Add {1} to your mana pool. {T}: Add one mana of any color to your mana pool. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

True-Name Nemesis

As True-Name Nemesis enters the battlefield, choose a player. True-Name Nemesis has protection from the chosen player. (This creature can't be blocked, targeted, dealt damage, or enchanted by anything controlled by that player.)

Venser, Shaper Savant

Flash (You may play this spell any time you could play an instant.) When Venser, Shaper Savant comes into play, return target spell or permanent to its owner's hand.

Phantasmal Image

You may have Phantasmal Image enter the battlefield as a copy of any creature on the battlefield, except it's an Illusion in addition to its other types and it gains "When this creature becomes the target of a spell or ability, sacrifice it."

Master of the Pearl Trident

Other Merfolk creatures you control get +1/+1 and have islandwalk. (They are unblockable as long as defending player controls an Island.)

Waterfront Bouncer

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

Misdirection

You may remove a blue card in your hand from the game instead of paying Misdirection's mana cost. Target spell with a single target targets another target instead.

Mental Misstep

({U/P} can be paid with either {U} or 2 life.) Counter target spell with converted mana cost 1.

Merrow Reejerey

Other Merfolk creatures you control get +1/+1. Whenever you play a Merfolk spell, you may tap or untap target permanent.

Umezawa's Jitte

Whenever equipped creature deals combat damage, put two charge counters on Umezawa's Jitte. Remove a charge counter from Umezawa's Jitte: Choose one — Equipped creature gets +2/+2 until end of turn; or target creature gets -1/-1 until end of turn; or you gain 2 life. Equip {2}

Dismember

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

Flusterstorm

Counter target instant or sorcery spell unless its controller pays {1}. Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Cursecatcher

Sacrifice Cursecatcher: Counter target instant or sorcery spell unless its controller pays {1}.

Energy Flux

All artifacts in play now require an upkeep cost of {2} in addition to any other upkeep costs they may have. If the upkeep cost for an artifact is not paid, the artifact must be discarded.

Mox Sapphire

Add 1 blue mana to your mana pool. Tapping this artifact can be played as an interrupt.

Lord of Atlantis

All Merfolk in play gain islandwalk and +1/+1 while this card is in play.

Time Walk

Take an extra turn after this one.

Ancestral Recall

Draw 3 cards or force opponent to draw 3 cards.

Black Lotus

Adds 3 mana of any single color of your choice to your mana pool, then is discarded. Tapping this artifact can be played as an interrupt.

Annul

Counter target artifact or enchantment spell.

Null Rod

Players cannot play any artifact abilities requiring an activation cost.

Ravenous Trap

If an opponent had three or more cards put into his or her graveyard from anywhere this turn, you may pay {0} rather than pay Ravenous Trap's mana cost. Exile all cards from target player's graveyard.

Echoing Truth

Strip Mine

Wasteland

Silvergill Adept

As an additional cost to cast this spell, reveal a Merfolk card from your hand or pay {3}. When Silvergill Adept enters the battlefield, draw a card.

Grafdigger's Cage

Creature cards in graveyards and libraries can't enter the battlefield. Players can't cast spells from graveyards or libraries.