Geier Reach Sanitarium

{T}: Add {C}.
{2}, {T}: Each player draws a card, then discards a card.

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Island

Persistent Petitioners

{1}, {T}: Target player mills a card. (They put the top card of their library into their graveyard.)
Tap four untapped Advisors you control: Target player mills twelve cards.
A deck can have any number of cards named Persistent Petitioners.

Howling Mine

At the beginning of each player's draw step, if Howling Mine is untapped, that player draws an additional card.

Visions of Beyond

Draw a card. If a graveyard has twenty or more cards in it, draw three cards instead.

Bruvac the Grandiloquent

If an opponent would mill one or more cards, they mill twice that many cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

Sol Ring

Traumatize

Target player mills half their library, rounded down.

Sage's Row Denizen

Whenever another blue creature you control enters, target player mills two cards.

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Herald's Horn

As Herald's Horn enters, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Kami of the Crescent Moon

At the beginning of each player's draw step, that player draws an additional card.

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Spellseeker

When Spellseeker enters, you may search your library for an instant or sorcery card with mana value 2 or less, reveal it, put it into your hand, then shuffle.

Mana Severance

Search your library for any number of land cards, exile them, then shuffle.

High Tide

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.