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.)

Harbinger of the Tides

You may cast Harbinger of the Tides as though it had flash if you pay {2} more to cast it. (You may cast it any time you could cast an instant.) When Harbinger of the Tides enters the battlefield, you may return target tapped creature an opponent controls to its owner's hand.

Chalice of the Void

Chalice of the Void enters the battlefield with X charge counters on it. Whenever a player casts a spell with converted mana cost equal to the number of charge counters on Chalice of the Void, counter that spell.

Aether Vial

At the beginning of your upkeep, you may put a charge counter on ?ther Vial. {T}: You may put a creature card with converted mana cost equal to the number of charge counters on ?ther Vial from your hand onto the battlefield.

Mutavault

{T}: Add {1} to your mana pool. {1}: Mutavault becomes a 2/2 creature with all creature types until end of turn. It's still a land.

Vendilion Clique

Flash Flying When Vendilion Clique enters the battlefield, look at target player's hand. You may choose a nonland card from it. If you do, that player reveals the chosen card, puts it on the bottom of his or her library, then draws a card.

Cursecatcher

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

Gemstone Caverns

If Gemstone Caverns is in your opening hand and you're not playing first, you may begin the game with Gemstone Caverns in play with a luck counter on it. If you do, remove a card in your hand from the game. {T}: Add {1} to your mana pool. If Gemstone Caverns has a luck counter on it, instead add one mana of any color to your mana pool.

Lord of Atlantis

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

Echoing Truth

Smuggler's Copter

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.