Merfolk Trickster

Flash
When this creature enters, tap target creature an opponent controls. It loses all abilities until end of turn.

Thought Collapse

Counter target spell. Its controller mills three cards.

Mirrormade

You may have this enchantment enter as a copy of any artifact or enchantment on the battlefield.

Venture Deeper

Target player mills four cards. (Then exile this card. You may cast the creature later from exile.)

Merfolk Secretkeeper

Merfolk Secretkeeper // Venture Deeper

Wizard's Retort

This spell costs {1} less to cast if you control a Wizard.
Counter target spell.

Sleep

Tap all creatures target player controls. Those creatures don't untap during that player's next untap step.

Faerie Miscreant

Flying
When this creature enters, if you control another creature named Faerie Miscreant, draw a card.

Fraying Sanity

Enchant player
At the beginning of each end step, enchanted player mills X cards, where X is the number of cards put into their graveyard from anywhere this turn.

Jace, Wielder of Mysteries

If you would draw a card while your library has no cards in it, you win the game instead.
+1: Target player mills two cards. Draw a card.
−8: Draw seven cards. Then if your library has no cards in it, you win the game.

Gadwick, the Wizened

When Gadwick enters, draw X cards.
Whenever you cast a blue spell, tap target nonland permanent an opponent controls.

Vantress Gargoyle

Flying
This creature can't attack unless defending player has seven or more cards in their graveyard.
This creature can't block unless you have four or more cards in hand.
{T}: Each player mills a card.

Island

Drowned Secrets

Whenever you cast a blue spell, target player mills two cards.

Mystic Sanctuary

({T}: Add {U}.)
This land enters tapped unless you control three or more other Islands.
When this land enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Arcanis the Omnipotent

{T}: Draw three cards.
{2}{U}{U}: Return Arcanis to its owner's hand.

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Psychic Corrosion

Whenever you draw a card, each opponent mills two cards.

Memorial to Genius

This land enters tapped.
{T}: Add {U}.
{4}{U}, {T}, Sacrifice this land: Draw two cards.