Terror

Destroy target nonartifact, nonblack creature. It can't be regenerated.

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Island

Mox Jet

Mox Sapphire

Time Walk

Unholy Strength

Enchant creature
Enchanted creature gets +2/+1.

Volcanic Eruption

Destroy X target Mountains. Volcanic Eruption deals damage to each creature and each player equal to the number of Mountains put into a graveyard this way.

Paralyze

Enchant creature
When Paralyze enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.
At the beginning of the upkeep of enchanted creature's controller, that player may pay {4}. If the player does, untap the creature.

Strip Mine

{T}: Add {C}.
{T}, Sacrifice Strip Mine: Destroy target land.

Lord of Atlantis

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

Counterspell

Weakness

Enchant creature
Enchanted creature gets -2/-1.

Blue Elemental Blast

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

Twiddle

You may tap or untap target artifact, creature, or land.

Black Lotus

{T}, Sacrifice Black Lotus: Add three mana of any one color.

Flying Men

Timetwister

Each player shuffles their hand and graveyard into their library, then draws seven cards. (Then put Timetwister into its owner's graveyard.)

Wall of Spears

Defender (This creature can't attack.)
First strike

Underground Sea

Black Knight

First strike (This creature deals combat damage before creatures without first strike.)
Protection from white (This creature can't be blocked, targeted, dealt damage, or enchanted by anything white.)

Sinkhole

Merfolk of the Pearl Trident

Psychic Venom

Enchant land
Whenever enchanted land becomes tapped, Psychic Venom deals 2 damage to that land's controller.

Bog Wraith

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)